Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent									35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount									$ 35,718	$ 0	$ 0
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Deferred Tax Amount									4,800
Income Tax Expense (Benefit)	$ 35,069	$ (339)	$ 1,524	$ (1,113)	$ (490)	$ 1,845	$ 1,077	$ 1,082	$ 35,141	$ 3,514	$ 1,200
Effective Income Tax Rate Reconciliation, Percent									(1176.90%)	64.10%	(61.80%)
Deferred Tax Liability, Tax Valuation Allowance	$ 0				$ 0				$ 0	$ 0
Eligibility Date to File with Consolidated Federal Income Tax Return									Dec. 31, 2020