Goodwill and Other Intangible Assets - Goodwill and Other Intangibles (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Total	$ 121,673	$ 127,340
Core deposit intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	146,838	148,679
Accumulated amortization	(39,941)	(36,871)
Total	106,897	111,808	$ 79,807
Books of Business Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	19,938	20,350
Accumulated amortization	(5,162)	(4,818)
Total	$ 14,776	$ 15,532	$ 11,527