Earnings per Unit and Dilution Computations (Units) (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings per Unit and Dilution Computations
Weighted Average Limited Partnership Units Outstanding, Basic	179.7	164.2	164.0
Weighted Average Number of Shares Outstanding, Basic	179.7	164.2	164.0
Weighted Average Number Diluted Shares Outstanding Adjustment			0.3
Total weighted average diluted common units outstanding (in units)	179.7	164.2	164.3