New Accounting Standards (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unrealized holding gain on the transfer of held-to-maturity securities to available-for-sale per ASU 2017-12			$ 2,547	$ 0	$ 0
Operating lease, right-of-use asset			40,700
Lease liability included in other liabilities			40,854
Accounting Standards Update 2018-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Software implementation costs, not yet capitalized			$ 3,800
Accounting Standards Update 2017-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fair value of HTM municipal bonds		$ 216,400
Unrealized holding gain on the transfer of held-to-maturity securities to available-for-sale per ASU 2017-12		$ 2,500
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset						$ 32,800
Lease liability included in other liabilities						$ 32,800
Forecast | Minimum | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan and lease losses, period increase, percent	1.40%
Forecast | Maximum | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan and lease losses, period increase, percent	1.50%