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	270,508				268,626		268,626	1,882
Other comprehensive income (loss)	33,414		33,414				33,414
Treasury stock purchases (in shares)						384
Treasury stock purchases	(20,558)					(20,558)	(20,558)
Exercise of stock options (in shares)		690				244
Exercise of stock options	11,526			24,726		(13,200)	11,526
Tax benefit on exercise of stock options	(487)			(487)			(487)
Stock-based compensation	6,334			6,334			6,334
Cash dividends on common stock	(73,666)				(73,666)		(73,666)
Issuance of non-controlling interest in subsidiary	1,645							1,645
Capital calls and distributions, net	(2,893)							(2,893)
Balance, end of period at Sep. 30, 2012	3,012,475	4	162,393	849,390	2,148,292	(184,422)	2,975,657	36,818
Balance, end of period (in shares) at Sep. 30, 2012		72,223				4,008
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	245,009				243,633		243,633	1,376
Other comprehensive income (loss)	(152,546)		(152,546)				(152,546)
Treasury stock purchases (in shares)						0
Treasury stock purchases	0					0	0
Exercise of stock options (in shares)		675				214
Exercise of stock options	14,945			26,317		(11,372)	14,945
Tax benefit on exercise of stock options	301			301			301
Stock-based compensation	4,537			4,537			4,537
Cash dividends on common stock	(77,486)				(77,486)		(77,486)
Issuance of non-controlling interest in subsidiary	0							0
Capital calls and distributions, net	(1,467)							(1,467)
Balance, end of period at Sep. 30, 2013	$ 3,026,974	$ 4	$ (2,626)	$ 890,433	$ 2,303,688	$ (200,255)	$ 2,991,244	$ 35,730
Balance, end of period (in shares) at Sep. 30, 2013		73,090				4,302