Consolidated Statements of Changes in Equity (Unaudited) (USD $) In Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total Shareholders' Equity [Member]	Non-Controlling Interests [Member]
Balance, beginning of period at Dec. 31, 2012	$ 2,993,681	$ 4	$ 859,278	$ 2,137,541	$ (188,883)	$ 149,920	$ 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)
Issuance of shares for equity compensation (in shares)		614			202
Issuance of shares for equity compensation	12,879		23,425		(10,546)		12,879
Tax effect from equity compensation, net	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	884,238	2,253,810	(199,429)	19,014	2,957,637	35,245
Balance, end of period (in shares) at Jun. 30, 2013		73,029			4,290
Balance, beginning of period at Dec. 31, 2013	3,054,973	4	898,586	2,349,428	(202,346)	(25,623)	3,020,049	34,924
Balance, beginning of period (in shares) at Dec. 31, 2013		73,163			4,305
Net income	153,772			152,485			152,485	1,287
Other comprehensive income (loss)	75,039					75,039	75,039
Issuance of shares for equity compensation (in shares)		734			306
Issuance of shares for equity compensation	(9,376)		10,964		(20,340)		(9,376)
Tax effect from equity compensation, net	7,333		7,333				7,333
Stock-based compensation	21,782		21,782				21,782
Cash dividends on common stock	(54,795)			(54,795)			(54,795)
Capital calls and distributions, net	(1,082)							(1,082)
Balance, end of period at Jun. 30, 2014	$ 3,247,646	$ 4	$ 938,665	$ 2,447,118	$ (222,686)	$ 49,416	$ 3,212,517	$ 35,129
Balance, end of period (in shares) at Jun. 30, 2014		73,897			4,611