Derivative Financial Instruments Interest rate swaps designated as cash flow hedges (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Weighted average pay rates	2.37%	2.37%
Weighted average receive rates	2.30%	2.57%
Weighted average maturity	5 years 11 months	6 years 2 months
Unrealized (losses) gains	$ (589,000)	$ 860,000
Interest Rate Swap [Member]
Derivative [Line Items]
Notional amount	$ 110,000	$ 110,000,000