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)	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 interest	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
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)	182,372			182,642			182,642	(270)
Other comprehensive income	74,140					74,140	74,140
Repurchase of common stock (in shares)					305
Repurchase of common stock	(17,771)				$ (17,771)		(17,771)
Issuance of shares for equity compensation (in shares)		336			15
Issuance of shares for equity compensation	5,418		5,513		$ (95)		5,418
Tax effect from equity compensation, net	589		589				589
Share-based compensation	7,569		7,569				7,569
Cash dividends on common stock	(84,832)			(84,832)			(84,832)
Capital calls and distributions, net	(2,713)							(2,713)
Balance, end of period (in shares) at Sep. 30, 2016		74,866			8,956
Balance, end of period at Sep. 30, 2016	$ 3,432,411	$ 4	$ 995,680	$ 2,801,931	$ (495,031)	$ 95,727	$ 3,398,311	$ 34,100