13. Employee benefit plans and deferred compensation

        We have 401(k) plans for the benefit of employees who meet certain eligibility requirements. The plans provide for company match, specified company contributions and discretionary company contributions. During the years ended September 30, 2015, 2014 and 2013, we contributed $4.7 million, $4.3 million and $3.8 million to the 401(k) plans, respectively.

        We also have a deferred compensation plan, which is a non-qualified plan available to a restricted number of highly compensated employees. The plan enables participants to defer compensation for tax purposes. These deferred employee contributions are held within a rabbi trust with investments directed by the respective employees. The assets of the rabbi trust are available to satisfy the claims of general creditors in the event of bankruptcy. The assets of the plan are sufficient to meet 90% of the liabilities as of September 30, 2015. The assets within the rabbi trust include $8.7 million invested in mutual funds which have quoted prices in active markets. These assets, as well as the related employee liabilities, are recorded at fair value with changes in fair value being recorded in the statement of operations.