Accumulated Other Comprehensive Income - AOCI Rollforward with Reclassification (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period	$ 25,207	$ 37,956	$ 24,258	$ 50,727
Balance at January 1, 2018, as adjusted					$ 50,073
Other comprehensive (loss) income	(905)	620	(2,336)	516
Balance, end of period	20,183	32,737	20,183	32,737
Total Accumulated Other Comprehensive Income
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period	39,325	36,546	40,768	(3,852)
Cumulative effect of adoption of ASU 2016-01					40,495
Balance at January 1, 2018, as adjusted					36,643
Other comprehensive income (loss) arising during the period	(900)	614	(2,375)	528
Amounts reclassified from accumulated other comprehensive income	(6)	6	26	(5)
Other comprehensive (loss) income	(906)	620	(2,349)	523
Balance, end of period	38,419	37,166	38,419	37,166
Unrealized Gains (Losses) on Available-for-Sale Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period	47	(967)	(160)	(566)
Cumulative effect of adoption of ASU 2016-01					40
Balance at January 1, 2018, as adjusted					(526)
Other comprehensive income (loss) arising during the period	51	(44)	271	(474)
Amounts reclassified from accumulated other comprehensive income	(6)	6	(19)	(5)
Other comprehensive (loss) income	45	(38)	252	(479)
Balance, end of period	92	(1,005)	92	(1,005)
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period	(3,286)	(3,286)	(3,286)	(3,286)
Cumulative effect of adoption of ASU 2016-01					0
Balance at January 1, 2018, as adjusted					(3,286)
Other comprehensive income (loss) arising during the period	0	0	0	0
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive (loss) income	0	0	0	0
Balance, end of period	(3,286)	(3,286)	(3,286)	(3,286)
Change in Fair Value of Debt Attributable to Instrument-Specific Credit Risk
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period	42,564	40,799	44,259	0
Cumulative effect of adoption of ASU 2016-01					40,455
Balance at January 1, 2018, as adjusted					$ 40,455
Other comprehensive income (loss) arising during the period	(951)	658	(2,646)	1,002
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive (loss) income	(951)	658	(2,646)	1,002
Balance, end of period	41,613	$ 41,457	41,613	$ 41,457
Equity in Other Comprehensive (Loss) Income of Limited Liability Investment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period			(45)
Other comprehensive income (loss) arising during the period			0
Amounts reclassified from accumulated other comprehensive income			45
Other comprehensive (loss) income			45
Balance, end of period	$ 0		$ 0