Benefit Plans Fair Value of Plan Assets (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	79,020,000		65,084,000
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	40,137,000		34,662,000
Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	38,883,000		30,422,000
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7,056,000		4,301,000
Cash and Cash Equivalents [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7,056,000		4,301,000
Cash and Cash Equivalents [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Cash and Cash Equivalents [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	35,091,000	[1]	27,209,000	[2]
Fixed Income Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[1]	0	[2]
Fixed Income Funds [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	35,091,000	[1]	27,209,000	[2]
Fixed Income Funds [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[1]	0	[2]
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations	55.00%		55.00%
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations	45.00%		45.00%
U.S. Large Cap Equity [Member] | Actively Managed Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22,749,000	[3]	3,716,000	[3]
U.S. Large Cap Equity [Member] | Actively Managed Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22,749,000	[3]	3,716,000	[3]
U.S. Large Cap Equity [Member] | Actively Managed Investments [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[3]	0	[3]
U.S. Large Cap Equity [Member] | Actively Managed Investments [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[3]	0	[3]
U.S. Large Cap Equity [Member] | Passive Index Fund ETFs [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			5,525,000	[4]
U.S. Large Cap Equity [Member] | Passive Index Fund ETFs [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			5,525,000	[4]
U.S. Large Cap Equity [Member] | Passive Index Fund ETFs [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[4]
U.S. Large Cap Equity [Member] | Passive Index Fund ETFs [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[4]
U.S. Mid Cap Equity [Member] | Actively Managed Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,989,000	[3]
U.S. Mid Cap Equity [Member] | Actively Managed Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,989,000	[3]
U.S. Mid Cap Equity [Member] | Actively Managed Investments [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[3]
U.S. Mid Cap Equity [Member] | Actively Managed Investments [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[3]
U.S. Mid Cap Equity [Member] | Passive Index Fund ETFs [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			69,000	[4]
U.S. Mid Cap Equity [Member] | Passive Index Fund ETFs [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			69,000	[4]
U.S. Mid Cap Equity [Member] | Passive Index Fund ETFs [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[4]
U.S. Mid Cap Equity [Member] | Passive Index Fund ETFs [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[4]
U.S. Small Mid Cap Equity [Member] | Actively Managed Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			1,814,000	[3]
U.S. Small Mid Cap Equity [Member] | Actively Managed Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			1,814,000	[3]
U.S. Small Mid Cap Equity [Member] | Actively Managed Investments [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[3]
U.S. Small Mid Cap Equity [Member] | Actively Managed Investments [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[3]
U.S. Small Mid Cap Equity [Member] | Passive Index Fund ETFs [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			617,000	[4]
U.S. Small Mid Cap Equity [Member] | Passive Index Fund ETFs [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			617,000	[4]
U.S. Small Mid Cap Equity [Member] | Passive Index Fund ETFs [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[4]
U.S. Small Mid Cap Equity [Member] | Passive Index Fund ETFs [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[4]
U.S. Small Cap Equity [Member] | Actively Managed Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,174,000	[3]	6,303,000	[3]
U.S. Small Cap Equity [Member] | Actively Managed Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,174,000	[3]	6,303,000	[3]
U.S. Small Cap Equity [Member] | Actively Managed Investments [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[3]	0	[3]
U.S. Small Cap Equity [Member] | Actively Managed Investments [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[3]	0	[3]
U.S. Small Cap Equity [Member] | Passive Index Fund ETFs [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			143,000	[4]
U.S. Small Cap Equity [Member] | Passive Index Fund ETFs [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			143,000	[4]
U.S. Small Cap Equity [Member] | Passive Index Fund ETFs [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[4]
U.S. Small Cap Equity [Member] | Passive Index Fund ETFs [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[4]
Emerging Market Equity [Member] | Actively Managed Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			3,547,000	[3]
Emerging Market Equity [Member] | Actively Managed Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			3,547,000	[3]
Emerging Market Equity [Member] | Actively Managed Investments [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[3]
Emerging Market Equity [Member] | Actively Managed Investments [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[3]
Non-U.S. Large Cap Equity [Member] | Actively Managed Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,169,000	[3]	4,271,000	[3]
Non-U.S. Large Cap Equity [Member] | Actively Managed Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,169,000	[3]	4,271,000	[3]
Non-U.S. Large Cap Equity [Member] | Actively Managed Investments [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[3]	0	[3]
Non-U.S. Large Cap Equity [Member] | Actively Managed Investments [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[3]	0	[3]
Non-U.S. Large Cap Equity [Member] | Passive Index Fund ETFs [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			4,356,000	[4]
Non-U.S. Large Cap Equity [Member] | Passive Index Fund ETFs [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			4,356,000	[4]
Non-U.S. Large Cap Equity [Member] | Passive Index Fund ETFs [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[4]
Non-U.S. Large Cap Equity [Member] | Passive Index Fund ETFs [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			0	[4]
REIT [Member] | Passive Index Fund ETFs [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,792,000	[3]	3,213,000	[4]
REIT [Member] | Passive Index Fund ETFs [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[3]	0	[4]
REIT [Member] | Passive Index Fund ETFs [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,792,000	[3]	3,213,000	[4]
REIT [Member] | Passive Index Fund ETFs [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[3]	0	[4]

[1] Actively managed portfolio of fixed income securities with the goal to exceed the Barclays 1-5 Year Government/Credit, Barclays Intermediate Government/Credit, and Merrill Lynch Preferred Stock Fixed Rate.

[2] Actively managed portfolio of fixed income securities with the goal to exceed the Barclays Capital Aggregate Bond, Barclays Capital 1-3 Year Government/Credit, and Merrill Lynch High Yield Master II performance.

[3] Actively managed portfolio of securities with the goal to exceed the stated benchmark performance.

[4] Open-ended fund of securities with the goal to track the stated benchmark performance.