Fair Value Fair Value of Pension Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 31,776	$ 39,369	$ 39,826
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31,776	39,369
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	197
Fair Value, Inputs, Level 1 [Member] | Bond Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,721	10,928
Fair Value, Inputs, Level 1 [Member] | Large Cap Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15,117	14,369
Fair Value, Inputs, Level 1 [Member] | International Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,967	5,994
Fair Value, Inputs, Level 1 [Member] | Small Cap Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,960	2,489
Fair Value, Inputs, Level 1 [Member] | Blended Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,185	1,998
Fair Value, Inputs, Level 1 [Member] | Mid Cap Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 3,826	$ 3,394