Securities - Gross Unrealized Losses and Fair Value of Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Securities in unrealized loss position, Less Than 12 Months, Fair Value	$ 42,835	$ 170,801
Securities in unrealized loss position, Less Than 12 Months, Unrealized Losses	460	1,181
Securities in unrealized loss position, 12 Months or More, Fair Value	36,610	67,639
Securities in unrealized loss position, 12 Months or More, Unrealized Losses	475	2,413
Securities in unrealized loss position, Total, Fair Value	79,445	238,440
Securities in unrealized loss position, Total, Unrealized Losses	935	3,594
US Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Securities in unrealized loss position, Less Than 12 Months, Fair Value		4,966
Securities in unrealized loss position, Less Than 12 Months, Unrealized Losses		3
Securities in unrealized loss position, Total, Fair Value		4,966
Securities in unrealized loss position, Total, Unrealized Losses		3
US government agencies
Schedule Of Available For Sale Securities [Line Items]
Securities in unrealized loss position, 12 Months or More, Fair Value		16,268
Securities in unrealized loss position, 12 Months or More, Unrealized Losses		225
Securities in unrealized loss position, Total, Fair Value		16,268
Securities in unrealized loss position, Total, Unrealized Losses		225
Mortgage-backed securities
Schedule Of Available For Sale Securities [Line Items]
Securities in unrealized loss position, Less Than 12 Months, Fair Value	42,835	164,836
Securities in unrealized loss position, Less Than 12 Months, Unrealized Losses	460	1,177
Securities in unrealized loss position, 12 Months or More, Fair Value	36,518	51,371
Securities in unrealized loss position, 12 Months or More, Unrealized Losses	467	2,188
Securities in unrealized loss position, Total, Fair Value	79,353	216,207
Securities in unrealized loss position, Total, Unrealized Losses	927	3,365
Municipal bonds
Schedule Of Available For Sale Securities [Line Items]
Securities in unrealized loss position, Less Than 12 Months, Fair Value		999
Securities in unrealized loss position, Less Than 12 Months, Unrealized Losses		1
Securities in unrealized loss position, 12 Months or More, Fair Value	92
Securities in unrealized loss position, 12 Months or More, Unrealized Losses	8
Securities in unrealized loss position, Total, Fair Value	92	999
Securities in unrealized loss position, Total, Unrealized Losses	$ 8	$ 1