Consolidated Statements of Changes in Equity (Unaudited) (USD $) In Thousands	Total	Common Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total shareholders' Equity [Member]	Non-Controlling Interest [Member]
Balance, beginning of period at Dec. 31, 2011	$ 2,786,652	$ 4	$ 128,979	$ 818,817	$ 1,953,332	$ (150,664)	$ 2,750,468	$ 36,184
Balance, beginning of period (in shares) at Dec. 31, 2011		71,533				3,380
Net income (loss)	83,193				83,615		83,615	(422)
Other comprehensive income (loss)	32,439		32,439				32,439
Treasury stock purchases (in shares)						345
Treasury stock purchases	(18,432)					(18,432)	(18,432)
Exercise of stock options (in shares)		369				60
Exercise of stock options	7,101			9,598		(2,497)	7,101
Tax benefit on exercise of stock options	(428)			(428)			(428)
Stock-based compensation	2,004			2,004			2,004
Cash dividends on common stock	(22,348)				(22,348)		(22,348)
Capital calls and distributions, net	220							220
Balance, end of period at Mar. 31, 2012	2,870,401	4	161,418	829,991	2,014,599	(171,593)	2,834,419	35,982
Balance, end of period (in shares) at Mar. 31, 2012		71,902				3,785
Balance, beginning of period at Dec. 31, 2012	2,993,681	4	149,920	859,278	2,137,541	(188,883)	2,957,860	35,821
Balance, beginning of period (in shares) at Dec. 31, 2012		72,415				4,088
Net income (loss)	89,059				87,964		87,964	1,095
Other comprehensive income (loss)	(16,537)		(16,537)				(16,537)
Treasury stock purchases (in shares)						0
Treasury stock purchases	0					0	0
Exercise of stock options (in shares)		531				170
Exercise of stock options	9,542			18,178		(8,636)	9,542
Tax benefit on exercise of stock options	(337)			(337)			(337)
Stock-based compensation	(751)			(751)			(751)
Cash dividends on common stock	(25,783)				(25,783)		(25,783)
Capital calls and distributions, net	982							(982)
Balance, end of period at Mar. 31, 2013	$ 3,047,892	$ 4	$ 133,383	$ 876,368	$ 2,199,722	$ (197,519)	$ 3,011,958	$ 35,934
Balance, end of period (in shares) at Mar. 31, 2013		72,946				4,258