Related Party Transactions (Details) - Director [Member] - USD ($) $ in Millions	3 Months Ended		5 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Targa Resource Partners L P [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	$ 1.5	$ 0.1		$ 14.3	$ 13.9
Accounts Payable, Related Parties	1.0		$ 1.0	1.0		$ 0.9
Methvin Company [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party	4.1		6.7
Accounts Receivable, Related Parties, Current	$ 1.3		$ 1.3	$ 1.3