Income Taxes - Changes in Balance of Deferred Tax Asset Valuation Allowance (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred Tax Asset Valuation Allowance [Roll Forward]
Beginning Balance	$ (33,757)	$ (49,562)	$ (36,419)
Additions	(1,895)	(4,359)	(20,182)
Deductions	4,884	20,164	7,039
Ending Balance	$ (30,768)	$ (33,757)	$ (49,562)