Earnings Per Share (Tables)

3 Months Ended

Mar. 31, 2013

Earnings Per Share [Abstract]

Numerator and denominator used to compute basic and diluted earnings per share

Additionally, the convertible senior notes were excluded from the computation of diluted earnings per share for the 2012 periods because their effect would have been antidilutive.

	Three Months Ended March 31,				Six Months Ended March 31,
	2013		2012		2013		2012
	(In millions)
Numerator:
Net income	$	111.0	$	40.6	$	177.3	$	68.3
Effect of dilutive securities:
Interest expense and amortization of issuance costs associated with convertible senior notes, net of tax	5.8		—		11.5		—
Numerator for diluted earnings per share after assumed conversions	$	116.8	$	40.6	$	188.8	$	68.3
Denominator:
Denominator for basic earnings per share — weighted average common shares	321.7		317.6		321.4		317.0
Effect of dilutive securities:
Employee stock awards	5.1		2.5		4.7		1.3
Convertible senior notes	38.6		—		38.6		—
Denominator for diluted earnings per share — adjusted weighted average common shares	365.4		320.1		364.7		318.3