CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Net income attributable to Targa Resources Corp.	$ 13.4	$ 9.6
Other comprehensive income (loss) attributable to Targa Resources Corp.
Net income attributable to noncontrolling interests	(20.4)	(59.6)
Pre-Tax [Member]
Other comprehensive income (loss) attributable to Targa Resources Corp.
Other comprehensive income (loss) attributable to Targa Resources Corp.	(1.9)	2.2
Other comprehensive income (loss) attributable to noncontrolling interests
Other comprehensive income (loss) attributable to noncontrolling interests	(10.6)	13.1
Related Income Tax [Member]
Other comprehensive income (loss) attributable to Targa Resources Corp.
Other comprehensive income (loss) attributable to Targa Resources Corp.	0.8	(0.9)
Other comprehensive income (loss) attributable to noncontrolling interests
Other comprehensive income (loss) attributable to noncontrolling interests	0	0
After Tax [Member]
Net income attributable to Targa Resources Corp.	13.4	9.6
Other comprehensive income (loss) attributable to Targa Resources Corp.
Other comprehensive income (loss) attributable to Targa Resources Corp.	(1.1)	1.3
Comprehensive income attributable to Targa Resources Corp.	12.3	10.9
Net income attributable to noncontrolling interests	20.4	59.6
Other comprehensive income (loss) attributable to noncontrolling interests
Other comprehensive income (loss) attributable to noncontrolling interests	(10.6)	13.1
Comprehensive income attributable to noncontrolling interests	9.8	72.7
Total comprehensive income	22.1	83.6
Commodity Contract [Member] | Pre-Tax [Member]
Other comprehensive income (loss) attributable to Targa Resources Corp.
Change in fair value	(1.2)	2.4
Settlements reclassified to revenues	(0.9)	(0.6)
Other comprehensive income (loss) attributable to noncontrolling interests
Change in fair value	(6.4)	13.1
Settlements reclassified to revenues	(5.7)	(1.9)
Commodity Contract [Member] | Related Income Tax [Member]
Other comprehensive income (loss) attributable to Targa Resources Corp.
Change in fair value	0.5	(0.9)
Settlements reclassified to revenues	0.4	0.2
Other comprehensive income (loss) attributable to noncontrolling interests
Change in fair value	0	0
Settlements reclassified to revenues	0	0
Commodity Contract [Member] | After Tax [Member]
Other comprehensive income (loss) attributable to Targa Resources Corp.
Change in fair value	(0.7)	1.5
Settlements reclassified to revenues	(0.5)	(0.4)
Other comprehensive income (loss) attributable to noncontrolling interests
Change in fair value	(6.4)	13.1
Settlements reclassified to revenues	(5.7)	(1.9)
Interest Rate Swap [Member] | Pre-Tax [Member]
Other comprehensive income (loss) attributable to Targa Resources Corp.
Settlements reclassified to interest expense, net	0.2	0.4
Other comprehensive income (loss) attributable to noncontrolling interests
Settlements reclassified to interest expense, net	1.5	1.9
Interest Rate Swap [Member] | Related Income Tax [Member]
Other comprehensive income (loss) attributable to Targa Resources Corp.
Settlements reclassified to interest expense, net	(0.1)	(0.2)
Other comprehensive income (loss) attributable to noncontrolling interests
Settlements reclassified to interest expense, net	0	0
Interest Rate Swap [Member] | After Tax [Member]
Other comprehensive income (loss) attributable to Targa Resources Corp.
Settlements reclassified to interest expense, net	0.1	0.2
Other comprehensive income (loss) attributable to noncontrolling interests
Settlements reclassified to interest expense, net	$ 1.5	$ 1.9