Employee Benefit Plans - Fair Value of Pension Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 5,653	$ 7,556	$ 7,647	$ 8,428
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,784	2,853
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,869	4,703
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	359	617
Cash | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	359	617
Cash | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Government sponsored entities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,119	1,892
Government sponsored entities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Government sponsored entities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,119	1,892
Government sponsored entities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Municipal bonds and notes
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,513	1,931
Municipal bonds and notes | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Municipal bonds and notes | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,513	1,931
Municipal bonds and notes | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate bonds and notes
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	237	880
Corporate bonds and notes | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate bonds and notes | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	237	880
Corporate bonds and notes | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. companies
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,227	1,768
U.S. companies | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,227	1,768
U.S. companies | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. companies | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign companies
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	198	468
Foreign companies | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	198	468
Foreign companies | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign companies | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0