Benefit Plans (Fair Value Measurement) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	$ 95,437	$ 83,638
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	81,273	69,340
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	14,164	14,298
Equity Securities [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	46,446	41,326
Equity Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	46,446	41,326
U.S. Treasury Securities [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	16,418	14,488
U.S. Treasury Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	16,418	14,488
Corporate Bonds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	11,743	11,340
Corporate Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	11,743	11,340
Mutual Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	10,360	9,491
Mutual Funds [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	10,360	9,491
Cash And Money Market Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	6,354	2,153
Cash And Money Market Funds [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	6,354	2,153
U.S. Government Agency Securities [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	2,421	2,958
U.S. Government Agency Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	2,421	2,958
Trust Preferred Securities [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	1,695	1,882
Trust Preferred Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, Fair Value Disclosure	$ 1,695	$ 1,882