Income Tax Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Mar. 21, 2018
Income Tax Disclosure [Abstract]
Effective tax rate, percentage	27.90%		(93.50%)	24.10%	70.00%
Federal NOL carryback period				10 years
Income tax benefit, revaluation of deferred tax assets						$ 115,291
Income tax benefit, reversal of valuation allowance for AMT credits						154,384
Financial statement benefit, NOL carryback		$ 20,000
Total amount of uncertain tax positions	$ 39,953			$ 39,953		37,813
Unrecognized tax benefits that would impact effective tax rate	31,516			31,516		29,376
Change in unrecognized tax benefits				2,140
Accrued interest liability	897			897		$ 644
Accrued interest expense	$ 252			$ 252
Reduction of net operating loss							$ 108,651