Shareholders' Equity - Summary of Preferred and Common Share Activity (Detail) (USD $)	12 Months Ended							12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Preferred Stock [Member]	Dec. 31, 2012 Preferred Stock [Member]	Dec. 31, 2011 Preferred Stock [Member]	Dec. 31, 2010 Preferred Stock [Member]	Dec. 31, 2013 Common Stock [Member]	Dec. 31, 2012 Common Stock [Member]	Dec. 31, 2011 Common Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Balance, Preferred Stock, Issued, Beginning Balance				0	0	0	0
Balance, Preferred Stock, Issued, Ending Balance				0	0	0	0
Balance, Common Stock, Issued, Beginning Balance	105,812,123							105,812,123	112,312,123	119,812,123
Retirement of treasury stock, Issued								(5,000,000)	(6,500,000)	(7,500,000)
Balance, Common Stock, Issued, Ending Balance	100,812,123	105,812,123						100,812,123	105,812,123	112,312,123
Treasury Stock, beginning balance	(11,576,487)			0	0	0	0	(11,576,487)	(11,732,658)	(947,497)
Grants of restricted stock	147,660	149,720	173,553					50,943	69,720	173,553
Forfeitures of restricted stock										$ (7,153)
Forfeitures and surrenders of restricted stock								$ (24,906)
Issuance of common stock due to exercise of stock options, Treasury Stock	2,611,838	5,354,381	4,829,892					2,611,838	5,357,490	4,829,892
Issuance of common stock due to settlement of restricted stock units								7,460
Treasury stock acquired								(7,379,384)	(11,771,039)	(23,281,453)
Retirement of treasury stock	5,000,000	6,500,000	7,500,000					5,000,000	6,500,000	7,500,000
Treasury Stock, ending balance	(11,310,536)	(11,576,487)		0	0	0	0	(11,310,536)	(11,576,487)	(11,732,658)