Income Taxes - Reconciliation of Unrecognized Tax Benefit (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 48,838	$ 51,244	$ 47,379
Additions based on tax positions related to the current year	9,179	9,073	15,411
Additions for tax positions of prior years	2,438		1,607
Reductions for tax positions of prior years			(293)
Reductions for audit settlements			(895)
Reductions resulting from a lapse of the applicable statute of limitations periods	(9,376)	(11,479)	(11,965)
Balance at end of year	$ 51,079	$ 48,838	$ 51,244