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 [Member]	Total Shareholders' Equity [Member]	Non-Controlling Interests [Member]
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 (loss)	155,367			154,073			154,073	1,294
Other comprehensive income (loss)	(4,881)					(4,881)	(4,881)
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)		425			91
Issuance of shares for equity compensation	5,739		9,744		$ (4,005)		5,739
Tax effect from equity compensation, net	744		744				744
Share-based compensation	4,922		4,922				4,922
Cash dividends on common stock	(57,660)			(57,660)			(57,660)
Sale of non-controlling interest	5,500							5,500
Capital calls and distributions, net	(3,620)							(3,620)
Balance, end of period (in shares) at Jun. 30, 2015		74,429			5,483
Balance, end of period at Jun. 30, 2015	3,412,833	$ 4	970,054	2,627,250	$ (273,468)	51,792	3,375,632	37,201
Balance, beginning of period (in shares) at Dec. 31, 2015		74,530			8,636
Balance, beginning of period at Dec. 31, 2015	3,267,639	$ 4	982,009	2,704,121	$ (477,165)	21,587	3,230,556	37,083
Net income (loss)	107,260			108,365			108,365	(1,105)
Other comprehensive income (loss)	96,045					96,045	96,045
Repurchase of common stock (in shares)					305
Repurchase of common stock	(17,770)				$ (17,770)		(17,770)
Issuance of shares for equity compensation (in shares)		287			10
Issuance of shares for equity compensation	2,276		2,016		$ 260		2,276
Tax effect from equity compensation, net	351		351				351
Share-based compensation	5,730		5,730				5,730
Cash dividends on common stock	(56,720)			(56,720)			(56,720)
Capital calls and distributions, net	(2,073)							(2,073)
Balance, end of period (in shares) at Jun. 30, 2016		74,817			8,951
Balance, end of period at Jun. 30, 2016	$ 3,402,738	$ 4	$ 990,106	$ 2,755,766	$ (494,675)	$ 117,632	$ 3,368,833	$ 33,905