Financial Statements of Guarantors (Details 4) (USD $) In Millions, unless otherwise specified	6 Months Ended	9 Months Ended	6 Months Ended	9 Months Ended	6 Months Ended	9 Months Ended	6 Months Ended	9 Months Ended	6 Months Ended	9 Months Ended	3 Months Ended
	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011 QCII	Sep. 30, 2012 QCII	Sep. 30, 2011 QSC and QCF	Sep. 30, 2012 QSC and QCF	Sep. 30, 2011 Subsidiaries Non-Guarantors	Sep. 30, 2012 Subsidiaries Non-Guarantors	Sep. 30, 2011 Eliminations	Sep. 30, 2012 Eliminations	Mar. 31, 2011 Predecessor	Mar. 31, 2011 Predecessor QCII	Mar. 31, 2011 Predecessor QSC and QCF	Mar. 31, 2011 Predecessor Subsidiaries Non-Guarantors	Mar. 31, 2011 Predecessor Eliminations
Financial Statements of Guarantors
Net cash (used in) provided by operating activities	$ 1,544	$ 2,017	$ (130)	$ (479)	$ 188	$ (169)	$ 1,486	$ 2,678		$ (13)	$ 777	$ 7	$ (62)	$ 828	$ 4
INVESTING ACTIVITIES
Payments for property, plant and equipment and capitalized software	(748)	(1,121)					(748)	(1,121)			(410)			(410)
Changes in interest in investments managed by QSC													(3)	3
Cash infusion to subsidiaries					(348)				348				(191)		191
Changes in advances to affiliates	(1,145)	(28)		395	(351)	221	(822)	(733)	28	89			180	1	(181)
Dividends received from subsidiaries			400	750	790	700			(1,190)	(1,450)			590		(590)
Proceeds from sale of property		133						133
Other, net	3						3				2			2
Net cash used in investing activities	(1,890)	(1,016)	400	1,145	91	921	(1,567)	(1,721)	(814)	(1,361)	(408)		576	(404)	(580)
FINANCING ACTIVITIES
Net proceeds from (repayments of) short-term affiliate debt			30		(2)				(28)			119	(300)		181
Net proceeds from issuance of long-term debt	1,200	896					1,200	896
Payments of long-term debt	(877)	(2,761)		(1,302)			(877)	(1,459)			(203)		(179)	(24)
Early retirement of debt costs	(13)	(178)					(13)	(178)
Dividends paid to parent	(300)	(750)	(300)	(750)	(400)	(750)	(790)	(700)	1,190	1,450	(141)	(141)		(590)	590
Changes in notes payable-affiliates		1,985								1,985
Changes in accounts payable-affiliates		(187)		1,386		(4)		492		(2,061)
Cash infusion from parent							348		(348)					191	(191)
Other, net	(18)						(18)				27	15		16	(4)
Net cash used in financing activities	(8)	(995)	(270)	(666)	(402)	(754)	(150)	(949)	814	1,374	(317)	(7)	(479)	(407)	576
Net (decrease) increase in cash and cash equivalents	(354)	6			(123)	(2)	(231)	8			52		35	17
Cash and cash equivalents at beginning of period	424	48			183	40	241	8			372		148	224
Cash and cash equivalents at end of period	$ 70	$ 54			$ 60	$ 38	$ 10	$ 16			$ 424		$ 183	$ 241