Fair Value Measurements and Disclosures (Details) - Fair Value - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets and Liabilities at Fair Value
Total assets	$ 109,015	$ 178,214
Total liabilities	(3,614)	(4,728)
Net asset (fair value)	105,401	173,486
Significant Other Observable Inputs (Level 2)
Assets and Liabilities at Fair Value
Total assets	77,313	118,521
Total liabilities	(2,817)	(3,364)
Net asset (fair value)	74,496	115,157
Significant Unobservable Inputs (Level 3)
Assets and Liabilities at Fair Value
Total assets	31,702	59,693
Total liabilities	(797)	(1,364)
Net asset (fair value)	$ 30,905	$ 58,329