Employer Sponsored Benefit Plans - Trust Assets at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	$ 87,452	$ 44,174
Measured at NAV	28,039	20,414
Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	13,941	11,577
Measured at NAV	0	0
International equities
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	9,547	11,626
Measured at NAV	0	0
Fixed income
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	38,704	17,360
Measured at NAV	27,727	17,360
U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	2,466
Measured at NAV	0
Corporate and foreign bonds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	1,448
Measured at NAV	0
Inflation hedge mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	2,808
Measured at NAV	0
Hedge fund of funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	4,441	3,054
Measured at NAV	312	3,054
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	14,097	557
Measured at NAV	0	0
Level 1
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	53,429	23,760
Level 1 | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	13,941	11,577
Level 1 | International equities
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	9,547	11,626
Level 1 | Fixed income
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	10,977	0
Level 1 | U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0
Level 1 | Corporate and foreign bonds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0
Level 1 | Inflation hedge mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	2,808
Level 1 | Hedge fund of funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	4,129	0
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	12,027	557
Level 2
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	5,984	0
Level 2 | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 2 | International equities
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 2 | Fixed income
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 2 | U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	2,466
Level 2 | Corporate and foreign bonds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	1,448
Level 2 | Inflation hedge mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0
Level 2 | Hedge fund of funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	2,070	0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3 | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3 | International equities
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3 | Fixed income
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3 | U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0
Level 3 | Corporate and foreign bonds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0
Level 3 | Inflation hedge mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0
Level 3 | Hedge fund of funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0	0
Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	$ 0	$ 0