Income Taxes - Components of income tax provision (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Dec. 22, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current
Federal
State and local			(626)	(741)	(601)
Current			(626)	(741)	(601)
Deferred
Federal			77,533	1,160	1,726
State and local			11,095	172	232
Deferred			$ 88,628	1,332	1,958
Statutory federal income tax rate (as a percent)	21.00%		34.00%
Increase (decrease) resulting from:
Income tax (benefit) at federal rate			$ (6,541)	577	835
State income taxes, net of federal income tax			(813)	101	104
Permanent difference for compensation limitation					637
Expense not deductible for tax				292	98
Tax credit included in taxable income			238	283	252
Other permanent differences			71	20	110
Capital goods excise tax credit			(626)	(741)	(601)
Change in federal income tax rate			28,018
Other, net			132	74	54
Change in valuation allowance		$ 89,400	67,523	(15)	(132)
Total income tax provision (benefit)			$ 88,002	$ 591	$ 1,357