Stockholders' Equity - Reconciliation of Beginning and End of Period Equity Accounts (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule Of Stockholders Equity [Line Items]
Beginning Balance			$ 843,792
Beginning Balance			884,261
Beginning Balance			40,469
Net income	$ 59,582	$ 38,182	100,343	$ 83,616
Net income	60,476	44,758	102,638	96,486
Net income	(894)	(6,576)	(2,295)	(12,870)
Other comprehensive income	6,577	$ 5,126	9,101	$ 7,478
Share repurchase program			(60,046)
Stock compensation plans			22,711
Cash dividends - $.210 per share			(12,050)
Ending Balance	905,503		905,503
Ending Balance	946,615		946,615
Ending Balance	41,112		41,112
Total Parent Stockholders' Equity [Member]
Schedule Of Stockholders Equity [Line Items]
Beginning Balance			843,792
Net income			100,343
Other comprehensive income			10,753
Share repurchase program			(60,046)
Stock compensation plans			22,711
Cash dividends - $.210 per share			(12,050)
Ending Balance	905,503		905,503
Noncontrolling Shareholders' Interests in Consolidated Subsidiaries [Member]
Schedule Of Stockholders Equity [Line Items]
Beginning Balance			40,469
Net income			2,295
Other comprehensive income			(1,652)
Ending Balance	$ 41,112		$ 41,112