Employee Benefit Plans Employee Benefit Plans 12 (Details) - SERP - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Balance in Rabbi Trust
Balance in Rabbi Trust	$ 16,400
Fair value of assets held in Rabbi Trust	0	$ 0
Rabbi Trust | Level 1
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	16,412	15,227
Rabbi Trust | Level 2
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	0	0
Rabbi Trust | Level 3
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	0	0
Rabbi Trust | Cash equivalents | Level 1
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	166	45
Rabbi Trust | Cash equivalents | Level 2
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	0	0
Rabbi Trust | Cash equivalents | Level 3
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	0	0
Rabbi Trust | Fixed income fund | Level 1
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	6,251	6,072
Rabbi Trust | Fixed income fund | Level 2
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	0	0
Rabbi Trust | Fixed income fund | Level 3
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	0	0
Rabbi Trust | Equity securities | Level 1
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	9,995	9,110
Rabbi Trust | Equity securities | Level 2
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	0	0
Rabbi Trust | Equity securities | Level 3
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	0	0
Fair Value | Rabbi Trust
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	16,412	15,227
Fair Value | Rabbi Trust | Cash equivalents
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	166	45
Fair Value | Rabbi Trust | Fixed income fund
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	6,251	6,072
Fair Value | Rabbi Trust | Equity securities
Balance in Rabbi Trust
Fair value of assets held in Rabbi Trust	$ 9,995	$ 9,110