Income Taxes - Difference Between Total Tax Expense and Amount Computed by Applying Statutory Federal Income Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Statutory rate applied to income	$ 393,288	$ 391,209	$ 365,506
Plus state income taxes, net of Federal tax benefit	32,295	32,646	28,823
Earnings in jurisdictions taxed at rates different from the statutory US tax rate	(13,684)	(3,453)	(37,873)
Foreign tax credit	(264)	(20,170)
Capital loss expiration			16,803
Reversal of capital loss valuation allowance			(16,803)
Other	6,374	6,221	2,889
Income tax expense, total	$ 418,009	$ 406,453	$ 359,345