Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Provision of Income Taxes [Line Items]
Current	$ 146,400	$ 238,500	$ 135,700
Deferred	48,800	13,300	90,200
Income taxes	195,173	251,777	225,882
Federal
Reconciliation of Provision of Income Taxes [Line Items]
Current	93,300	115,400	68,400
Deferred	49,200	12,900	90,400
Income taxes	142,500	128,300	158,800
State
Reconciliation of Provision of Income Taxes [Line Items]
Current	3,100	4,900	4,600
Deferred	(400)	400	(200)
Income taxes	2,700	5,300	4,400
Foreign
Reconciliation of Provision of Income Taxes [Line Items]
Current	50,000	118,200	62,700
Income taxes	$ 50,000	$ 118,200	$ 62,700