Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2011

Stock-Based Compensation [Abstract]

Stock Options

	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Terms (Years)		Aggregate Intrinsic Value
	(in millions)
Options outstanding at December 31, 2010		880,087		$	16.35
Granted		—			—
Exercised		(226,571	)	$	16.51
Cancelled		—			—
Options outstanding at December 31, 2011		653,516		$	16.30		5.3	$	9.0
Options exercisable:
December 31, 2010		449,587		$	16.46		3.1	$	4.6
December 31, 2011		223,016		$	16.42		2.1	$	3.0

Restricted Stock

	Number of Restricted Share Awards			Weighted Average Fair Value per Award
Restricted share awards outstanding at December 31, 2010		2,976,128		$	24.79
Granted		925,140			34.21
Vested		(745,147	)		25.62
Forfeited		(93,460	)		26.17
Restricted share awards outstanding at December 31, 2011		3,062,661		$	27.39