Income Taxes - The components of the net deferred income tax asset (liability) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Depreciation and amortization	$ 10,210	$ 9,297
Deferred revenue	2,115	655
Net operating loss carryforwards	74,656	71,330
Alternative minimum tax credit carryforward	2,523	2,523
Research and development tax credit carryforward	0	566
Accrued expenses and other	7,891	8,211
Total deferred tax assets	97,395	92,582
Deferred tax liabilities:
Depreciation and amortization	(3,315)	(4,186)
Intangible assets	(487)	(1,854)
Deferred expenses and other	(138)	(127)
Total deferred tax liabilities	(3,940)	(6,167)
Valuation allowance:
Beginning balance	(88,737)	0
Increase during the period	(6,675)	(88,737)
Total valuation allowance	(95,412)	(88,737)
Net deferred tax asset (liability)	(1,957)	(2,322)
Deferred income tax asset	257	39
Deferred income tax liability	$ (2,214)	$ (2,361)