Consolidated Statements of Changes in Equity (Unaudited) - USD ($) shares in Thousands, $ 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 (in shares) at Dec. 31, 2013		73,163			4,305
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
Net income	229,898			228,117			228,117	1,781
Other comprehensive income	48,918					48,918	48,918
Repurchase of common stock (in shares)					0
Repurchase of common stock					$ 0
Issuance of shares for equity compensation (in shares)		470			120
Issuance of shares for equity compensation	6,289		14,656		$ (8,367)		6,289
Tax effect from equity compensation, net	8,176		8,176				8,176
Share-based compensation	11,815		11,815				11,815
Issuance of shares in settlement of deferred compensation, net (in shares)		331			202
Issuance of shares in settlement of deferred compensation, net	1,936		15,072		$ (13,136)		1,936
Cash dividends on common stock	(82,207)			(82,207)			(82,207)
Capital calls and distributions, net	(2,486)							(2,486)
Balance, end of period (in shares) at Sep. 30, 2014		73,964			4,627
Balance, end of period at Sep. 30, 2014	3,277,312	$ 4	948,305	2,495,338	$ (223,849)	23,295	3,243,093	34,219
Balance, beginning of period (in shares) at Dec. 31, 2014		74,004			4,890
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
Net income	231,183			228,964			228,964	2,219
Other comprehensive income	29,103					29,103	29,103
Repurchase of common stock (in shares)					1,760
Repurchase of common stock	(109,760)				$ (109,760)		(109,760)
Issuance of shares for equity compensation (in shares)		457			98
Issuance of shares for equity compensation	4,797		10,728		$ (5,931)		4,797
Tax effect from equity compensation, net	645		645				645
Share-based compensation	7,807		7,807				7,807
Cash dividends on common stock	(86,509)			(86,509)			(86,509)
Sale of non-controlling interests	5,500							5,500
Capital calls and distributions, net	(2,810)							(2,810)
Balance, end of period (in shares) at Sep. 30, 2015		74,461			6,748
Balance, end of period at Sep. 30, 2015	$ 3,416,162	$ 4	$ 973,824	$ 2,673,292	$ (355,670)	$ 85,776	$ 3,377,226	$ 38,936