Summary of Significant Accounting Policies (Summary of Temporary Differences and Carry Forwards Which Give Rise to Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred tax liabilities
Property and equipment	$ (4,940)	$ (15,031)	$ (16,032)
Goodwill	(1,396)	(1,290)	(407)
Intangibles	(13,606)	(24,244)	(23,896)
Other	(1,132)	(1,386)	(2,350)
Gross deferred tax liabilities	(21,074)	(41,951)	(42,685)
Deferred tax assets
Net operating loss carryforwards	8,888	18,035	14,500
Deferred revenue and setup charges	3,435	4,323	3,747
Leases	453	2,154	3,097
Credits	543	492	630
Bad debt reserve	2,250	41	539
Other	1,607	2,114	1,752
Gross deferred tax assets	17,176	27,159	24,265
Net deferred tax liability	3,898	14,792	18,420
Valuation allowance	(713)	(393)	(393)
Net deferred tax liability	$ 4,611	$ 15,185	$ 18,813