Related Party Transactions (Details) - Director [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Targa Resource Partners L P [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party		$ 4.0	$ 4.7	$ 12.8
Accounts Payable, Related Parties					$ 2.0
Methvin Company [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party	$ 4.7	$ 2.6	7.7
Accounts Receivable, Related Parties, Current	$ 1.3		$ 1.3		$ 1.3