Variable Interest Entities and Other Investments - Summary of Investment in Limited Partnerships Subsequent to Adoption of ASU 2016-01 (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Variable Interest Entities and Other Investments [Line Items]
Equity method investments	$ 10,208	$ 8,714
Investments in Limited Partnerships
Variable Interest Entities and Other Investments [Line Items]
Affordable housing projects (amortized cost)	25,167	7,803
Limited partnerships accounted for under the fair value practical expedient of NAV	11,601	11,191
Limited partnerships without readily determinable fair values that do not qualify for the practical expedient of NAV accounted for under the cost method	10,208	8,714
Equity method investments	9,209	9,209
Total investments in limited partnerships	$ 56,185	$ 36,917