Fair Value Measurements - Narrative (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants outstanding (in shares)	0	675,000
Venture Lending and Leasing VI and VII
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants outstanding (in shares)			0	341,838
Lovoo Acquisition and Skout Acquisition [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, probability of payment	100.00%	100.00%