Income Tax (Provision for Income Tax Expense Computed from Statutory Rate to Pre-tax Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	$ 260,678	$ 352,987	$ 222,339
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount	(9,950)	(12,483)	(8,032)
Income Tax Reconciliation Foreign Income Tax Basis Differential	(32,472)	(8,256)	(26,484)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	19,157	2,076	26,507
Effective Income Tax Rate Reconciliation, Tax Contingency, Domestic, Amount	88	(9,083)	9,034
Income Tax Reconciliation Change In Canadian Enacted Tax Rate	0	0	(414)
Income Tax Reconciliation Change In Foreign Enacted Tax Rate	0	280	(1,184)
Income Tax Reconciliation Subpart F	3,473	6,132	8,255
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount	(1,936)	(1,045)	(1,786)
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount	1,482	(8,123)	(12,465)
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	2,109	2,001	647
Income Tax Expense (Benefit)	$ 242,629	$ 324,486	$ 216,417
Effective Income Tax Rate Reconciliation, Percent	32.60%	32.20%	34.10%