Income Taxes (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Income Taxes [Abstract]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	[1]	$ (64,151)	$ (2,272)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount		$ (9,164)	$ (195)
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent		3.00%	3.00%
Effective Income Tax Rate Reconciliation, Tax Benefit (Deficiency), Amount		$ 1,509	$ (3,300)
Effective Income Tax Rate Reconciliation, Tax Benefit (Deficiency), Percent		(0.50%)	50.80%
Effective Income Tax Rate Reconciliation, Valuation Allowance, Amount	[2]	$ (69)	$ (145)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent		0.00%	2.20%
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount		$ 339	$ (110)
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent		(0.10%)	1.70%
Provision for income taxes		$ (71,536)	$ (6,022)
Effective Income Tax Rate Reconciliation, Percent		23.40%	92.70%

[1] In December 2017 the Tax Cuts and Jobs Act was signed into law, which among other things reduced the U.S. federal corporate income tax rate from 35% to 21% effective January 1, 2018.

[2] Represents valuation allowances recognized against all deferred tax assets associated with operating loss carryforwards generated by the Company's Canadian operations during the respective periods for which the Company does not expect to realize a benefit.