Fair Value Recurring Basis (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value, assets, level 1 to level 2 transfers, amount	$ 0	$ 0
Fair value, assets, level 2 to level 1 transfers, amount	0	0
Fair value, liabilities, level 1 to level 2 transfers, amount	0	0
Fair value, liabilities, level 2 to level 1 transfers, amount	0	0
Fair Value, transfers into (out of) level 3	0	0
Fair Value, Measurements, Recurring [Member] | Total Net Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	17,018	6,650
Rabbi trust investments	19,819	16,477
Interest rate derivative liability	(1,644)
Total	35,193	23,127
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	17,018	6,650
Rabbi trust investments	19,819	16,477
Interest rate derivative liability	0
Total	36,837	23,127
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs(Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	0	0
Rabbi trust investments	0	0
Interest rate derivative liability	(1,644)
Total	(1,644)	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs(Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	0	0
Rabbi trust investments	0	0
Interest rate derivative liability	0
Total	0	0
Fair Value, Measurements, Recurring [Member] | Margin Cash Collateral Offset
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	0
Rabbi trust investments	0
Interest rate derivative liability	0
Total	$ 0