Pension Benefits Fair Value of Plan Assets in Heirarchy (Details) - USD ($)		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	[1]	7.50%	7.50%	7.50%
Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities		100.00%
Defined Benefit Plan, Asset Allocation		100.00%	100.00%
Defined Benefit Plan, Fair Value of Plan Assets		$ 31,731,000	$ 25,769,000	$ 27,940,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		5,214,000	5,045,000	$ 4,864,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		561,000	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		54,000	165,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		115,000	16,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(561,000)
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		19,481,000	17,754,000
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		7,036,000	2,970,000
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		$ 5,214,000	$ 5,045,000
Cash and Cash Equivalents [Member]
Defined Benefit Plan, Asset Allocation		0.00%	0.00%
Defined Benefit Plan, Fair Value of Plan Assets		$ 0	$ 0
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		0	0
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		0	0
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		$ 0	$ 0
Domestic Equity Securities [Member]
Defined Benefit Plan, Asset Allocation	[2]	18.70%	26.10%
Defined Benefit Plan, Fair Value of Plan Assets	[2]	$ 5,945,000	$ 6,729,000
Domestic Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[2]	4,471,000	4,943,000
Domestic Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[2]	1,474,000	1,786,000
Domestic Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[2]	$ 0	$ 0
International Equity Securities [Member]
Defined Benefit Plan, Asset Allocation	[3]	10.10%	13.00%
Defined Benefit Plan, Fair Value of Plan Assets	[3]	$ 3,192,000	$ 3,353,000
International Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[3]	3,192,000	3,353,000
International Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[3]	0	0
International Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[3]	$ 0	$ 0
Equity Securities [Member]
Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities		35.00%
Defined Benefit Plan, Asset Allocation		28.80%	39.10%
Defined Benefit Plan, Fair Value of Plan Assets		$ 9,137,000	$ 10,082,000
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		7,663,000	8,296,000
Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		1,474,000	1,786,000
Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		$ 0	$ 0
High-yield Bonds [Member]
Defined Benefit Plan, Asset Allocation	[4]	2.60%	2.80%
Defined Benefit Plan, Fair Value of Plan Assets	[4]	$ 822,000	$ 722,000
High-yield Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	822,000	722,000
High-yield Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	0	0
High-yield Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	$ 0	$ 0
Fixed Income Investments [Member]
Defined Benefit Plan, Asset Allocation	[5]	25.00%	22.50%
Defined Benefit Plan, Fair Value of Plan Assets	[5]	$ 7,923,000	$ 5,789,000
Fixed Income Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[5]	7,923,000	5,789,000
Fixed Income Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[5]	0	0
Fixed Income Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[5]	$ 0	$ 0
Floating Rate Corporate Debt [Member]
Defined Benefit Plan, Asset Allocation	[6]	7.90%	8.70%
Defined Benefit Plan, Fair Value of Plan Assets	[6]	$ 2,495,000	$ 2,247,000
Floating Rate Corporate Debt [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[6]	2,495,000	2,247,000
Floating Rate Corporate Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[6]	0	0
Floating Rate Corporate Debt [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[6]	$ 0	$ 0
Fixed Income Securities [Member]
Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities		43.00%
Defined Benefit Plan, Asset Allocation		35.50%	34.00%
Defined Benefit Plan, Fair Value of Plan Assets		$ 11,240,000	$ 8,758,000
Fixed Income Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		11,240,000	8,758,000
Fixed Income Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		0	0
Fixed Income Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		$ 0	$ 0
Commodity Contract [Member]
Defined Benefit Plan, Asset Allocation	[7]	1.80%	2.70%
Defined Benefit Plan, Fair Value of Plan Assets	[7]	$ 578,000	$ 700,000
Commodity Contract [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[7]	578,000	700,000
Commodity Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[7]	0	0
Commodity Contract [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[7]	$ 0	$ 0
Real Estate [Member]
Defined Benefit Plan, Asset Allocation	[8]	5.10%	5.80%
Defined Benefit Plan, Fair Value of Plan Assets	[8]	$ 1,629,000	$ 1,499,000
Real Estate [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[8]	0	0
Real Estate [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[8]	0	0
Real Estate [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[8]	$ 1,629,000	$ 1,499,000
Hedge Funds [Member]
Defined Benefit Plan, Asset Allocation	[9]	11.30%	13.80%
Defined Benefit Plan, Fair Value of Plan Assets	[9]	$ 3,585,000	$ 3,546,000
Hedge Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[9]	0	0
Hedge Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[9]	0	0
Hedge Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[9]	$ 3,585,000	$ 3,546,000
Collective Investment Trust [Member]
Defined Benefit Plan, Asset Allocation	[10]	17.50%	4.60%
Defined Benefit Plan, Fair Value of Plan Assets	[10]	$ 5,562,000	$ 1,184,000
Collective Investment Trust [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[10]	0	0
Collective Investment Trust [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[10]	5,562,000	1,184,000
Collective Investment Trust [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	[10]	$ 0	$ 0
Other Securities [Member]
Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities		22.00%
Defined Benefit Plan, Asset Allocation		35.70%	26.90%
Defined Benefit Plan, Fair Value of Plan Assets		$ 11,354,000	$ 6,929,000
Other Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		578,000	700,000
Other Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		5,562,000	1,184,000
Other Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Fair Value of Plan Assets		5,214,000	$ 5,045,000
Non Qualified Plan [Member]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets			0.00%	0.00%
Defined Benefit Plan, Fair Value of Plan Assets		$ 0	$ 0	$ 0

[1] There is no assumed expected return on plan assets for the Nonqualified Pension Plan because there are no plan assets in the Nonqualified Pension Plan.

[2] Level 1 equity securities consist of United States large and small capitalization companies, which are actively traded securities that can be sold upon demand. Level 2 equity securities are investments in a collective investment fund that is valued at net asset value based on the value of the underlying investments and total units outstanding on a daily basis. The objective of this fund is to approximate the S&P 500 by investing in one or more collective investment funds.

[3] International equity securities consists of a well-diversified portfolio of holdings of mostly large issuers organized in developed countries with liquid markets, commingled with investments in equity securities of issuers located in emerging markets and believed to have strong sustainable financial productivity at attractive valuations.

[4] High-yield bonds consist of non-investment grade fixed income securities. The investment objective is to obtain high current income. Due to the increased level of default risk, security selection focuses on credit-risk analysis.

[5] The objective of core fixed income funds is to achieve value added from sector or issue selection by constructing a portfolio to approximate the investment results of the Barclay’s Capital Aggregate Bond Index with a modest amount of variability in duration around the index.

[6] Investments consist of floating rate bank loans. The interest rates on these loans are typically reset on a periodic basis to account for changes in the level of interest rates.

[7] Investments with exposure to commodity price movements, primarily through the use of futures, swaps and other commodity-linked securities.

[8] The investment objective of direct real estate is to provide current income with the potential for long-term capital appreciation. Ownership in real estate entails a long-term time horizon, periodic valuations, and potentially low liquidity.

[9] The hedge fund portfolio includes an investment in an actively traded global mutual fund that focuses on alternative investments and a hedge fund of funds that invests both long and short using a variety of investment strategies.

[10] Collective investment trusts invest in short-term investments and are valued at the net asset value of the collective investment trust. The net asset value, as provided by the trustee, is used as a practical expedient to estimate fair value. The net asset value is based on the fair value of the underlying investments held by the fund less its liabilities.