Earnings Per Common Share (Basic and Diluted Earnings Per Common Share) (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Net income	$ 237,866	$ 237,952	$ 217,535
Less: Preferred stock dividends	6,719	0	0
Net income available to common shareholders	231,147	237,952	217,535
Less: Earnings allocated to participating securities	850	773	728
Net earnings allocated to common stock	230,297	237,179	216,807
Distributed earnings allocated to common stock	119,177	116,472	111,827
Undistributed earnings allocated to common stock	$ 111,120	$ 120,707	$ 104,980
Weighted-average shares outstanding for basic earnings per common share	60,350,552	61,298,041	61,101,072
Dilutive effect of stock compensation	765,858	345,341	176,697
Weighted-average shares outstanding for diluted earnings per common share	61,116,410	61,643,382	61,277,769