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, 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	77,043			76,590			76,590	453
Other comprehensive income	32,418						32,418
Repurchase of common stock (in shares)					0
Repurchase of common stock					0
Issuance of shares for equity compensation (in shares)		385			103
Issuance of shares for equity compensation	3,655		10,461		(6,806)		3,655
Tax effect from equity compensation, net	1,732		1,732				1,732
Share-based compensation	2,863		2,863				2,863
Cash dividends on common stock	(27,382)			(27,382)			(27,382)
Capital calls and distributions, net	(703)							(703)
Balance, end of period at Mar. 31, 2014	3,144,599	4	913,642	2,398,636	(209,152)	6,795	3,109,925	34,674
Balance, end of period (in shares) at Mar. 31, 2014		73,548			4,408
Balance, beginning of period at Dec. 31, 2014	3,336,206	4	954,644	2,530,837	(239,979)	56,673	3,302,179	34,027
Balance, beginning of period (in shares) at Dec. 31, 2014		74,004			4,890
Net income	75,094			74,843			74,843	251
Other comprehensive income	33,630					33,630	33,630
Repurchase of common stock (in shares)					502
Repurchase of common stock	(29,484)				(29,484)		(29,484)
Issuance of shares for equity compensation (in shares)		347			37
Issuance of shares for equity compensation	2,640		2,926		(286)		2,640
Tax effect from equity compensation, net	215		215				215
Share-based compensation	1,865		1,865				1,865
Cash dividends on common stock	(28,727)			(28,727)			(28,727)
Capital calls and distributions, net	(1,187)							(1,187)
Balance, end of period at Mar. 31, 2015	$ 3,390,252	$ 4	$ 959,650	$ 2,576,953	$ (269,749)	$ 90,303	$ 3,357,161	$ 33,091
Balance, end of period (in shares) at Mar. 31, 2015		74,351			5,429