Fair Value Measurements (Assets And Liabilities Measured On Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair Value Measurements [Line Items]
Short-term investments	$ 899
Derivative assets	13,620	9,926
Total assets	31,145	25,956
Derivative liabilities	537	768
Total liabilities	17,163	16,798
Grantor Trusts [Member]
Fair Value Measurements [Line Items]
Investments in grantor trusts	16,626	16,030
Deferred compensation plan obligations	16,626	16,030
Interest Rate Contracts [Member]
Fair Value Measurements [Line Items]
Derivative assets	13,620	9,926
Derivative liabilities	537	768
Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Fair Value Measurements [Line Items]
Short-term investments	899
Total assets	17,525	16,030
Total liabilities	16,626	16,030
Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member] | Grantor Trusts [Member]
Fair Value Measurements [Line Items]
Investments in grantor trusts	16,626	16,030
Deferred compensation plan obligations	16,626	16,030
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Measurements [Line Items]
Total assets	13,620	9,926
Total liabilities	537	768
Significant Other Observable Inputs (Level 2) [Member] | Interest Rate Contracts [Member]
Fair Value Measurements [Line Items]
Derivative assets	13,620	9,926
Derivative liabilities	537	768
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Measurements [Line Items]
Total assets	0	0
Total liabilities	$ 0	$ 0