Retirement Benefit Plans (Schedule of Fair Value of Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 25,711	$ 26,337
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9,686	10,717
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,025	15,620
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mid Cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,623	1,642
Mid Cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,623	1,642
Large Cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,411	5,162
Large Cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,411	5,162
International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,915	2,985
International | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,915	2,985
Liability Driven Solution
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,543	$ 3,702
Liability Driven Solution | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Liability Driven Solution | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,543	$ 3,702
Liability Driven Solution | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Wells Fargo International Equity Index Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,080	$ 1,098
Wells Fargo International Equity Index Fund | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,080	1,098
Wells Fargo Core Bond
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,774
Wells Fargo Core Bond | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,774
Wells Fargo Core Bond
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,810
Wells Fargo Core Bond | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,810
Wells Fargo/Causeway
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,112	1,118
Wells Fargo/Causeway | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,112	1,118
Wells Fargo Large Cap Growth Index Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,429	1,473
Wells Fargo Large Cap Growth Index Fund | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,429	1,473
Wells Fargo Large Cap Value Index Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,415	1,476
Wells Fargo Large Cap Value Index Fund | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,415	1,476
Wells Fargo Multi-Manager Small Cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,707	1,783
Wells Fargo Multi-Manager Small Cap | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,707	1,783
Wells Fargo Russell 2000 Index Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	800	860
Wells Fargo Russell 2000 Index Fund | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	800	860
Wells Fargo S&P Mid Cap Index Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	942	990
Wells Fargo S&P Mid Cap Index Fund | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	942	990
Wells Fargo/MFS Value CIT F
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	736
Wells Fargo/MFS Value CIT F | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	736
Wells Fargo/T Rowe Price I Large-Cap Growth Managed CIT
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	749
Wells Fargo/T Rowe Price I Large-Cap Growth Managed CIT | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	749
T. Rowe Price Equity Income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	738	1,310
T. Rowe Price Equity Income | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	738	1,310
Cash & Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	737	928
Cash & Short-term Investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 737	$ 928