Changes in Accumulated Other Comprehensive Loss, Net of Taxes, Related to Interest Rate Swap Agreements (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before reclassifications, net of taxes	$ 767	$ 892	$ 2,379	$ 2,050
Net other comprehensive income			2,379	2,050
Interest Rate Swap
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balances	(1,258)	(4,558)	(2,870)	(5,716)
Other comprehensive loss before reclassifications, net of taxes	(679)	(641)	(2,028)	(2,468)
Amounts reclassified from accumulated other comprehensive loss to interest expense, net of taxes	1,446	1,533	4,407	4,518
Net other comprehensive income	767	892	2,379	2,050
Ending balances	$ (491)	$ (3,666)	$ (491)	$ (3,666)