Revenue (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Retained Earnings (Accumulated Deficit), Total	$ (234,723)	$ (225,369)		$ (224,239)
Accounts receivable, net	66,202	60,102		66,437
Current portion of deferred revenue		8,102		12,489
Noncontrolling interest	70,726	71,547	$ 74,813	71,902
Deferred income taxes	67,002	67,799		$ 68,262
Net revenue	169,956	167,464	155,528
(Benefit from) provision for income taxes	(694)	(132,535)	$ 9,157
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Retained Earnings (Accumulated Deficit), Total		1,130
Accounts receivable, net		6,335
Current portion of deferred revenue		4,387
Noncontrolling interest		355
Deferred income taxes		$ 463
Net revenue	(3,553)
(Benefit from) provision for income taxes	$ (869)