Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowances for doubtful accounts	$ 734	$ 824
Accumulated depreciation on property and equipment	12,540	18,371
Accumulated amortization on intangible assets	66,639	55,298
Deferred loan costs, current	141	65
Deferred loan costs, non current	$ 0	$ 141
Common stock, par value (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	34,104,000	33,840,000
Treasury stock (in shares)	6,065,000	5,831,000