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Income Tax - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Income Tax Contingency [Line Items]      
Excess tax benefit from exercises of share-based arrangements $ 45,314,000 $ 19,402,000 $ 28,207,000
Deferred tax assets, valuation allowance $ 0    
Income tax examination, year under examination 2012    
Income taxes, net of refunds $ 27,300,000 10,200,000 $ 9,300,000
State [Member]      
Income Tax Contingency [Line Items]      
Income tax examination, year under examination 2011    
Stock Option Plan [Member]      
Income Tax Contingency [Line Items]      
Excess tax benefit from exercises of share-based arrangements $ 45,300,000 19,400,000  
Federal Income Tax [Member]      
Income Tax Contingency [Line Items]      
Net operating loss carryforwards for federal income tax   $ (650,000)