Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2014

Earnings Per Share [Abstract]

Schedule of computation of basic and diluted earnings per share

Computation of Earnings Per Share

	Year Ended December 31,
	2014		2013		2012
	(in millions, except per share amounts)
Basic EPS:
Net income (loss) attributable to AGL	$	1,088	$	808	110
Less: Distributed and undistributed income (loss) available to nonvested shareholders	0		1		0
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	1,088	$	807	110
Basic shares	172.6		186.6		189.2
Basic EPS	$	6.30	$	4.32	$	0.58
Diluted EPS:
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	1,088	$	807	$	110
Plus: Re-allocation of undistributed income (loss) available to nonvested shareholders of AGL and subsidiaries	0		0		0
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, diluted	$	1,088	$	807	$	110
Basic shares	172.6		186.6		189.2
Effect of dilutive securities:
Options and restricted stock awards	1.0		1.0		0.8
Equity units	—		—		0.7
Diluted shares	173.6		187.6		190.7
Diluted EPS	$	6.26	$	4.30	$	0.57
Potentially dilutive securities excluded from computation of EPS because of antidilutive effect	1.6		2.7		9.9

Schedule of antidilutive securities excluded from computation of earnings per share

Computation of Earnings Per Share

	Year Ended December 31,
	2014		2013		2012
	(in millions, except per share amounts)
Basic EPS:
Net income (loss) attributable to AGL	$	1,088	$	808	110
Less: Distributed and undistributed income (loss) available to nonvested shareholders	0		1		0
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	1,088	$	807	110
Basic shares	172.6		186.6		189.2
Basic EPS	$	6.30	$	4.32	$	0.58
Diluted EPS:
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	1,088	$	807	$	110
Plus: Re-allocation of undistributed income (loss) available to nonvested shareholders of AGL and subsidiaries	0		0		0
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, diluted	$	1,088	$	807	$	110
Basic shares	172.6		186.6		189.2
Effect of dilutive securities:
Options and restricted stock awards	1.0		1.0		0.8
Equity units	—		—		0.7
Diluted shares	173.6		187.6		190.7
Diluted EPS	$	6.26	$	4.30	$	0.57
Potentially dilutive securities excluded from computation of EPS because of antidilutive effect	1.6		2.7		9.9