Stock-Based Compensation Stock-Based Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation			$ 7,108	$ 6,516
Continuing Operations
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	3,625	3,795	7,108	6,518
Continuing Operations | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	3,512	3,683	6,884	6,293
Continuing Operations | Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 113	$ 112	$ 224	$ 225