Benefit Plans (Changes In Fair Value Of Plan Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	$ 215,775		$ 210,498
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	137,926		138,897
Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	66,269		61,372
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	11,580		10,229
Cash And Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	6,403	[1]	16,769	[1]
Cash And Cash Equivalents [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	6,205	[1]	16,522	[1]
Cash And Cash Equivalents [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	198	[1]	247	[1]
United States Large-Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	29,329		29,073
United States Large-Cap [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	6,460		7,645
United States Large-Cap [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	22,869		21,428
U.S. Mid-Cap And Small-Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	3,346		3,058
U.S. Mid-Cap And Small-Cap [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	3,346		3,058
International [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	80,409	[2]	88,361	[2]
International [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	73,388	[2]	81,713	[2]
International [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	7,021	[2]	6,648	[2]
Total Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	113,084		120,492
Total Equity Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	79,848		89,358
Total Equity Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	33,236		31,134
Corporate Bonds - Domestic [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	18,371		17,057
Corporate Bonds - Domestic [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	18,371		17,057
Corporate Bonds - International [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	28,950		27,651
Corporate Bonds - International [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	17,369		15,904
Corporate Bonds - International [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	11,581		11,747
UK Index-Linked Gilts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	22,041		17,113
UK Index-Linked Gilts [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	22,041		17,113
Diversified Domestic Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	1,594		1,187
Diversified Domestic Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	1,594		1,187
Total Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	70,956		63,008
Total Fixed Income Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	39,410		33,017
Total Fixed Income Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	31,546		29,991
U.S. Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	1,289	[3]	1,111	[3]
U.S. Real Estate [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	1,289	[3]
U.S. Real Estate [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets			1,111	[3]
International Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	12,463	[3]
International Real Estate [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	12,463	[3]
Other[Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	11,580	[4]	9,118	[4]
Other[Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	$ 11,580	[4]	$ 9,118	[4]

[1] Cash and cash equivalents consist of traditional domestic and foreign highly liquid short-term securities with the goal of providing liquidity and preservation of capital while maximizing return on assets.

[2] The International category consists of mutual fund investments focused on companies operating in developed and emerging markets outside of the U.S. These investments target broad diversification across large and mid/small-cap companies and economic sectors.

[3] U.S. and International real estate consists primarily of equity and debt investments made, directly or indirectly, in various interests in unimproved and improved real properties.

[4] Other investments consist of insurance and reinsurance contracts securing the retirement benefits. The fair value of these contracts was calculated at the discount value of premiums paid by the Company, less expenses charged by the insurance providers. The insurance providers with which the Company has placed these contracts are well-known financial institutions with an established history of providing insurance services.