Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Tax Reconciliation [Line Items]
Estimated effective income tax rate	(5.10%)	23.60%	37.10%	37.60%
Effective tax rate impacted by net tax benefit	$ 15,500,000		$ 15,500,000
Recognized tax benefit from uncertain tax positions	31,000,000		31,000,000
Reduction on deferred tax assets			15,500,000
Recognized tax benefits	(1,805,000)	12,567,000	24,311,000	30,335,000
Stock-based Incentive Plans [Member]
Income Tax Reconciliation [Line Items]
Recognized tax benefits	$ 25,100,000