Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Tax Disclosure [Abstract]
Provisions for income taxes	$ 8,949	$ 18,040	$ 21,820	$ 21,239
Effective income tax rate	21.90%	45.80%	22.70%	48.40%
Recognized discrete tax benefits	$ 4,400		$ 11,500
Statutory US federal income tax rate			35.00%
Income tax payments	4,100	$ 9,500	$ 49,600	$ 29,000
Prepaid income taxes	$ 20,900		$ 20,900