Benefit Plans Plan Assets (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 95,353	$ 79,020
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocations as a percent of toal plan assets	53.00%
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9,127	7,056
Actual plan asset allocations as a percent of toal plan assets	9.00%
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	91,358	75,542	62,763
Pension Plan [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	34,464	33,922
Actual plan asset allocations as a percent of toal plan assets	38.00%	45.00%
Pension Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	48,442	35,352
Actual plan asset allocations as a percent of toal plan assets	53.00%	47.00%
Pension Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8,452	6,268
Actual plan asset allocations as a percent of toal plan assets	9.00%	8.00%
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,995	3,478	2,321
Other Postretirement Benefit Plan [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,427	1,168
Actual plan asset allocations as a percent of toal plan assets	36.00%	33.00%
Other Postretirement Benefit Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,893	1,522
Actual plan asset allocations as a percent of toal plan assets	47.00%	44.00%
Other Postretirement Benefit Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 675	$ 788
Actual plan asset allocations as a percent of toal plan assets	17.00%	23.00%