Variable Interest Entities - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Investment in variable interest entities	$ 69,368	$ 69,459	$ 68,351
Advances to variable interest entities	6,418	5,633	5,077
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Investment in variable interest entities	63,320	64,281	62,156
Advances to variable interest entities	11,301	3,273	2,817
Guaranteed amounts to variable interest entities (not to exceed)	$ 61,566	$ 67,027	$ 73,278