Other Intangible Assets - Schedule of Other Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	$ 229,167	$ 28,999
Accumulated amortization	(13,257)	(8,503)
Net carrying amount	215,910	20,496
Core deposit intangibles
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	180,837	3,049
Accumulated amortization	(6,372)	(2,502)
Net carrying amount	174,465	547
Program agreements
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	14,700	14,700
Accumulated amortization	(868)	(408)
Net carrying amount	13,832	14,292
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	9,250	9,250
Accumulated amortization	(5,334)	(3,643)
Net carrying amount	3,916	5,607
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	24,380	2,000
Accumulated amortization	(683)	(1,950)
Net carrying amount	$ 23,697	$ 50