Fair Value Measurement (Tables)

6 Months Ended

12 Months Ended

Jun. 30, 2011

Dec. 31, 2010

Fair Value Measurement Abstract

Fair Value of Assets Measured on a Recurring Basis

Assets and liabilities measured at fair value on a recurring basis at June 30, 2011 are as follows:

	Fair value measurements						Total fair value
In millions	Level 1		Level 2		Level 3
Assets:
Cash and cash equivalents	$	1,259.8	$	—	$	—	$	1,259.8
Marketable securities	13.5		—		—		13.5
Derivative instruments	—		11.5		—		11.5
Benefit trust assets	19.9		158.7		—		178.6
Total	$	1,293.2	$	170.2	$	—	$	1,463.4
Liabilities:
Derivative instruments	$	—	$	7.5	$	—	$	7.5
Benefit trust liabilities	16.0		149.9		—		165.9
Total	$	16.0	$	157.4	$	—	$	173.4

Assets and liabilities measured at fair value on a recurring basis at December 31, 2010 are as follows:

	Fair value measurements						Total fair value
In millions	Level 1		Level 2		Level 3
Assets:
Cash and cash equivalents	$	1,014.3	$	—	$	—	$	1,014.3
Marketable securities	15.5		—		—		15.5
Derivative instruments	—		21.5		—		21.5
Benefit trust assets	17.3		155.2		—		172.5
Total	$	1,047.1	$	176.7	$	—	$	1,223.8
Liabilities:
Derivative instruments	$	—	$	2.6	$	—	$	2.6
Benefit trust liabilities	17.4		178.4		—		195.8
Total	$	17.4	$	181.0	$	—	$	198.4