Shareholders' Equity (Summary of Shares Outstanding) (Detail)	3 Months Ended	12 Months Ended							12 Months Ended
	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Common Stock	Dec. 31, 2012 Common Stock	Dec. 31, 2011 Common Stock	Dec. 31, 2010 Common Stock	Dec. 31, 2013 Treasury Stock	Dec. 31, 2012 Treasury Stock	Dec. 31, 2011 Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)	(153,566,297)	(153,566,297)	(151,888,780)	(160,381,815)	(290,573,068)	(290,573,068)	(290,573,068)	(290,573,068)	(137,006,771)	(138,684,288)	(130,191,253)
Treasury Stock, Shares, Acquired	(10,825,227)	(10,825,227)							(10,825,227)
Purchases (in shares)		(5,745,529)	(1,000,000)	(10,236,694)					(5,745,529)	(1,000,000)	(10,236,694)
Issuances (in shares)		1,650,841	2,677,517	1,743,659					1,650,841	2,677,517	1,743,659
Ending balance (in shares)		(138,646,382)	(153,566,297)	(151,888,780)	(290,573,068)	(290,573,068)	(290,573,068)	(290,573,068)	(151,926,686)	(137,006,771)	(138,684,288)