Quarterly report pursuant to Section 13 or 15(d)

Supplemental Disclosures

Supplemental Disclosures
6 Months Ended
Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Supplemental Disclosures Supplemental Disclosures
Under a resolution adopted in March 2020, the Board of Directors authorized the purchase, at management's discretion, of up to $200 million of our common stock. This supplemented a similar resolution adopted in June 2018. During the six months ended March 31, 2020, we purchased approximately 2,767,000 of our common shares at a cost of $167.0 million. During the six months ended March 31, 2019, we acquired approximately 716,000 common shares at a cost of $45.4 million. At March 31, 2020, $150.0 million remained available for future stock purchases.
During the six months ended March 31, 2020, we granted 316,000 restricted stock units to our board of directors and employees. These awards will vest ratably over one and five years, respectively.
Our deferred compensation plan uses both mutual fund and life insurance investments to fund its obligations. The mutual funds are recorded at fair value, based upon quoted prices in active markets, and the life insurance investments at cash surrender value; changes in value are reported in our consolidated statements of operations. At March 31, 2020, the deferred compensation plan held $18.4 million of the mutual fund investments.
The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and other amounts included within current assets and liabilities that meet the definition of a financial instrument are shown at values equivalent to fair value due to the short-term nature of these items. Our debt balances are principally from credit facilities which can be utilized and repaid as required and whose rates are based upon prevailing market conditions; accordingly, we believe the balance disclosed is consistent with fair value. Our accounts receivable billed and billable balance includes both amounts invoiced and amounts that are ready to be invoiced where the funds are collectible within standard invoice terms. Our accounts receivable unbilled balance includes balances where revenue has been earned but no invoice was issued on or before March 31, 2020. Restricted cash represents funds which are held in our bank accounts but which we are precluded from using for general business needs through contractual requirements; these requirements include serving as collateral for lease, credit card or letter of credit arrangements or where we hold funds on behalf of clients. Restricted cash is included within "prepaid expenses and other assets" on our balance sheet and is included within "cash, cash equivalents and restricted cash" in our consolidated statements of cash flows. A reconciliation of these balances is shown below.
  Balance as of
(dollars in thousands) March 30,
September 30, 2019 March 31,
September 30, 2018
Cash and cash equivalents $ 126,257    $ 105,565    $ 46,799    $ 349,245   
Restricted cash (recorded within "other current assets") 12,485    10,927    7,679    7,314   
Cash, cash equivalents and restricted cash 138,742    116,492    54,478    356,559   

During the six months ended March 31, 2020 and 2019, we made interest payments of $0.5 million and $1.8 million, respectively.
During the six months ended March 31, 2020 and 2019, we made income tax payments of $52.9 million and $37.2 million, respectively.