Financial Instruments (Details 6) (USD $)			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Unit adjustment liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of year			$ 0
Recognition of unit adjustment liability			107,500,000
Payments			(2,123,000)
Change in fair value to unit adjustment liability			966,000
Balance at end of year			106,343,000
Fair value of long-term debt	832,600,000	1,000,000,000
Carrying value of long-term debt	$ 803,415,000	$ 960,706,000