Annual report pursuant to Section 13 and 15(d)

Business and summary of significant accounting policies - Narrative (Details)

v3.19.3
Business and summary of significant accounting policies - Narrative (Details) - USD ($)
12 Months Ended
Jul. 01, 2019
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2017
Oct. 01, 2018
Property and Equipment          
Retained earnings   $ 794,739,000 $ 633,281,000   $ 666,210,000
Goodwill, impairment loss $ 0        
Impairment of long-lived assets held-for-use     $ 0 $ 0  
Accounting Standards Update 2014-09          
Property and Equipment          
Retained earnings         $ 32,900,000
Buildings | Maximum          
Property and Equipment          
Estimated useful lives   39 years      
Office furniture and equipment. | Maximum          
Property and Equipment          
Estimated useful lives   7 years      
Software development costs. | Minimum          
Property and Equipment          
Estimated useful lives   3 years      
Software development costs. | Maximum          
Property and Equipment          
Estimated useful lives   8 years      
U.S. Health and Human Services          
Property and Equipment          
Impairment loss on contract costs   $ 3,700,000