Stockholders' Equity - Reconciliation of Beginning and End of Period Equity Accounts (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Schedule Of Stockholders Equity [Line Items]
Beginning Balance	$ 979,248
Beginning Balance	1,017,611
Beginning Balance	38,363
Net income (loss)	59,005	$ 40,761
Net income (loss)	58,772	42,163
Net income (loss)	(233)	1,402
Other comprehensive income	2,632	$ 2,522
Share repurchase program	(24,826)
Stock compensation plans	5,948
Cash dividends - $0.105 per share	(5,817)
Ending Balance	1,016,388
Ending Balance	1,054,320
Ending Balance	37,932
Total Parent Stockholders' Equity [Member]
Schedule Of Stockholders Equity [Line Items]
Beginning Balance	979,248
Net income (loss)	59,005
Other comprehensive income	2,830
Share repurchase program	(24,826)
Stock compensation plans	5,948
Cash dividends - $0.105 per share	(5,817)
Ending Balance	1,016,388
Noncontrolling Shareholders' Interests in Consolidated Subsidiaries [Member]
Schedule Of Stockholders Equity [Line Items]
Beginning Balance	38,363
Net income (loss)	(233)
Other comprehensive income	(198)
Ending Balance	$ 37,932