Non-interest Revenue and Expense Non-interest Revenue and Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Total non-interest income	$ 1,148	$ 1,327	$ 1,079	$ 1,304	$ 10,665	$ 1,346	$ 1,139	$ 1,209	$ 4,858	$ 14,359
Noninterest income out of scope of Topic 606
Disaggregation of Revenue [Line Items]
Total non-interest income									1,157	10,366
Noninterest income in scope of Topic 606
Disaggregation of Revenue [Line Items]
Total non-interest income									3,701	3,993
Deposit Account [Member] | Noninterest income in scope of Topic 606
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer									3,337	3,372
Mortgage Banking [Member] | Noninterest income in scope of Topic 606
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer									303	530
Advertising [Member] | Noninterest income in scope of Topic 606
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer									$ 61	$ 91