Composition of Certain Financial Statement Captions - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 56,020	$ 57,870
Less: Accumulated depreciation and amortization	(21,578)	(19,015)
Property and equipment, net	34,442	38,855	$ 3,748
Estimated increase in combined amortization and depreciation expense due to acquired intangible assets and property and equipment measured at fair value	7,200	2,300	$ 1,600
Equipment, furniture and other
Property, Plant and Equipment [Line Items]
Property and equipment, gross	26,029	28,071
Building and improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	18,222	18,153
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	5,300	5,300
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 6,469	$ 6,346