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	182,654				181,243		181,243	1,411
Other comprehensive income (loss)	10,211		10,211				10,211
Treasury stock purchases (in shares)						384
Treasury stock purchases	(20,558)					(20,558)	(20,558)
Exercise of stock options (in shares)		473				98
Exercise of stock options	8,454			13,122		(4,668)	8,454
Tax benefit on exercise of stock options	(677)			(677)			(677)
Stock-based compensation	4,803			4,803			4,803
Cash dividends on common stock	(48,010)				(48,010)		(48,010)
Capital calls and distributions, net	(808)							(808)
Balance, end of period at Jun. 30, 2012	2,922,721	4	139,190	836,065	2,086,565	(175,890)	2,885,934	36,787
Balance, end of period (in shares) at Jun. 30, 2012		72,006				3,862
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	168,947				167,895		167,895	1,052
Other comprehensive income (loss)	(130,906)		(130,906)				(130,906)
Treasury stock purchases (in shares)						0
Treasury stock purchases	0					0	0
Exercise of stock options (in shares)		614				202
Exercise of stock options	12,879			23,425		(10,546)	12,879
Tax benefit on exercise of stock options	178			178			178
Stock-based compensation	1,357			1,357			1,357
Cash dividends on common stock	(51,626)				(51,626)		(51,626)
Capital calls and distributions, net	(1,628)							(1,628)
Balance, end of period at Jun. 30, 2013	$ 2,992,882	$ 4	$ 19,014	$ 884,238	$ 2,253,810	$ (199,429)	$ 2,957,637	$ 35,245
Balance, end of period (in shares) at Jun. 30, 2013		73,029				4,290