Leases (Tables)

12 Months Ended

Dec. 31, 2011

Leases

Schedule of expense related to operating leases

	Fuel and purchased energy expenses		Operating expenses		Total
	(In millions)
2011	$	291.1	$	31.7	$	322.8
2010		227.9		30.2		258.1
2009		385.6		37.2		422.8

Schedule of future minimum payments for long-term, noncancelable, operating leases

Year	Power Purchase Agreements		Other		Total
	(In millions)
2012	$	198.2	$	32.0	$	230.2
2013		190.9		29.6		220.5
2014		193.8		33.8		227.6
2015		193.3		19.8		213.1
2016		108.2		12.9		121.1
Thereafter		51.9		17.1		69.0
Total future minimum lease payments	$	936.3	$	145.2	$	1,081.5