Allowance for Doubtful Accounts (Details) (Allowance for Doubtful Accounts, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Allowance for Doubtful Accounts
Change in the allowance for doubtful accounts
Balance at the beginning of the period	$ 2,556	$ 2,583	$ 2,086
Bad debt expense	1,175	1,671	1,764
Uncollected accounts written off, net of recoveries	(1,979)	(1,698)	(1,336)
Allowance for doubtful accounts of acquired companies			69
Balance at the end of the period	$ 1,752	$ 2,556	$ 2,583