Disclosure About Fair Values of Financial Instruments - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Assets
Investment securities available-for-sale	$ 1,754,839	$ 1,187,252
Derivative assets	182,287	11,136
Liabilities
Derivative liabilities	24,046	32,350
Carrying Value
Assets
Investment securities available-for-sale	1,754,839	1,187,252
Equity securities with readily determinable fair values not held for trading	6,073	5,840
Derivative assets	182,287	11,136
Net profits interests	5,317	5,779
Liabilities
Derivative liabilities	24,046	32,350
Level 1
Assets
Equity securities with readily determinable fair values not held for trading	6,073	5,840
Level 2
Assets
Investment securities available-for-sale	1,754,839	1,187,252
Derivative assets	182,287	11,136
Liabilities
Derivative liabilities	24,046	32,350
Level 3
Assets
Net profits interests	5,317	$ 5,779
Fair Value, Measurements, Recurring | Carrying Value
Assets
Investment securities available-for-sale	1,754,839		$ 1,187,252
Equity securities with readily determinable fair values not held for trading	6,073		5,840
Derivative assets	182,287		11,136
Net profits interests	5,317		5,779
Other assets	15,403		11,191
Total recurring basis measured assets	1,963,919		1,221,198
Liabilities
Derivative liabilities	24,046		32,350
Total recurring basis measured liabilities	24,046		32,350
Fair Value, Measurements, Recurring | Level 1
Assets
Equity securities with readily determinable fair values not held for trading	6,073		5,840
Total recurring basis measured assets	6,073		5,840
Fair Value, Measurements, Recurring | Level 2
Assets
Investment securities available-for-sale	1,754,839		1,187,252
Derivative assets	182,287		11,136
Total recurring basis measured assets	1,937,126		1,198,388
Liabilities
Derivative liabilities	24,046		32,350
Total recurring basis measured liabilities	24,046		32,350
Fair Value, Measurements, Recurring | Level 3
Assets
Net profits interests	5,317		5,779
Other assets	15,403		11,191
Total recurring basis measured assets	$ 20,720		$ 16,970