Income Taxes (Tables)

6 Months Ended

Jun. 30, 2012

Income Tax Disclosure [Abstract]

Reconciliation of Income Tax Expense

The table below provides a reconciliation of income tax expense computed at the federal statutory income tax rate to the income tax provision.

	Three months ended June 30,						Six months ended June 30,
(in millions)	2012			2011			2012			2011
Income before income taxes	$	322		$	354		$	622		$	713
Provision for income tax at federal statutory rate of 35%	113			124			218			249
Increase (decrease) in income tax from:
State tax – net of federal benefit	10			18			20			30
Property-related	(10		)	(10		)	(20		)	(21		)
Other	(5		)	(4		)	(10		)	(7		)
Total income tax expense	$	108		$	128		$	208		$	251
Effective tax rate	33.5		%	36.2		%	33.4		%	35.2		%