Partnership Units and Related Matters (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended			1 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 August 2013 EDA [Member]	Apr. 18, 2014 August 2013 EDA [Member] Subsequent Event [Member]	Apr. 30, 2014 August 2013 EDA [Member] Subsequent Event [Member]
Partnership Equity [Abstract]
Number of common units sold (in shares)			2,222,271	802,630
Net proceeds from sale of common units			$ 115.3	$ 47.7
Receivables from issuance of common units					5.9
General partner contributed to maintain general partner ownership percentage			2.4	1.0
Receivables from contribution to maintain 2% general partner interest					1.2
General partner ownership interest (in hundredths)	2.00%		2.00%	2.00%
Aggregate amount of debt or equity securities allowed to be issued under the shelf agreement				7.4
Number of days from end of each quarter by when cash is distributed to unit holders	45 days
Date paid or to be paid	May 15, 2014	Feb. 14, 2014
Distributions Paid Limited Partners Common	87.2	84.0
Distributions to General Partners (Incentive)	31.7	29.5
Distributions to General Partners (2%)	2.4	2.3
Total distributions to general and limited partners	121.3	115.8
Distributions to Targa Resources Corp.	$ 44.0	$ 41.5
Distributions per limited partner per unit (in dollars per unit)	$ 0.7625	$ 0.7475