Subsequent Events (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended			3 Months Ended	1 Months Ended
	Mar. 31, 2013 Subsequent Event [Member]	Apr. 25, 2013 Subsequent Event [Member]	Jan. 15, 2013 Senior Secured Revolving Credit Facility [Member]	Mar. 31, 2013 Service Restricted Units [Member]	Apr. 30, 2013 Service Restricted Units [Member] Subsequent Event [Member]	Apr. 30, 2013 Performance Restricted Units [Member] Subsequent Event [Member]	Apr. 30, 2013 Independent Directors Of The Partnership [Member] Subsequent Event [Member]
Subsequent Event [Line Items]
Date distribution was declared	Apr. 25, 2013
Cash distribution per unit		$ 0.4875
Date distribution will be paid	May 15, 2013
Date unitholders of record	May 08, 2013
Credit Agreement, current borrowing capacity			$ 900.0
Restricted units granted to employees				4,000	441,000	149,000	20,000