Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Income tax expense (benefit)
Interest and penalties expense (benefit) relating to uncertain tax positions			$ 200	$ (300)
Accrued interest and penalties relating to uncertain tax positions	$ 2,600		2,600		$ 2,500
Income taxes	$ 37,684	$ 35,109	$ 68,281	$ 66,119