Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent Beginning Balance	$ 2,894,582
Net Income (Loss) Attributable to Parent	26,238	$ 27,019
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	23,831	23,613
Adjustments to Additional Paid in Capital, Share-based Compensation and Exercise of Stock Options	3,601
Stockholders' Equity Attributable to Parent Ending Balance	2,948,252
Stockholders' Equity Attributable to Noncontrolling Interest Beginning Balance	292,539
Net Income Attributable to Noncontrolling Interest	1,051	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	12,035
Stockholders' Equity, Other	(32)
Stockholders' Equity Attributable to Noncontrolling Interest Ending Balance	305,593
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Beginning Balance	3,187,121
Net income	27,289	27,019
Other Comprehensive Income (Loss), Net of Tax	35,866	$ 23,613
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Ending Balance	3,253,845
Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Share-based Compensation and Exercise of Stock Options	3,601
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity, Other	$ (32)