Stockholders' Equity - Reconciliation of Beginning and End of Period Equity Accounts (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Schedule Of Stockholders Equity [Line Items]
Beginning Balance	$ 990,866
Beginning Balance	1,157,625
Balance at December 31, 2013	166,759
Reclassification of redeemable noncontrolling shareholder interest	(152,250)
Net income	47,428
Other comprehensive income	3,348
Other comprehensive income	2,352	9,132
Balance at March 31, 2014	44,604
Stock compensation plans	800
Cash dividends - $.105 per share	(6,656)
Ending Balance	1,005,691
Ending balance	1,050,295
Noncontrolling Shareholder Interest in Consolidated Subsidiary [Member]
Schedule Of Stockholders Equity [Line Items]
Balance at December 31, 2013	166,759
Reclassification of redeemable noncontrolling shareholder interest	(123,965)
Net income	1,994
Other comprehensive income	(184)
Balance at March 31, 2014	44,604
Total Parent Stockholders' Equity [Member]
Schedule Of Stockholders Equity [Line Items]
Beginning Balance	990,866
Reclassification of redeemable noncontrolling shareholder interest	(28,285)
Net income	45,434
Other comprehensive income	3,532
Stock compensation plans	800
Cash dividends - $.105 per share	(6,656)
Ending Balance	1,005,691
Redeemable Noncontrolling Shareholder Interest [Member]
Schedule Of Stockholders Equity [Line Items]
Beginning Balance
Reclassification of redeemable noncontrolling shareholder interest	152,250
Net income	4,300
Other comprehensive income	(996)
Ending Balance	$ 155,554