Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Schedule of computation of basic and diluted earnings per share

Computation of Earnings Per Share

	Year Ended December 31,
	2016		2015		2014
	(in millions, except per share amounts)
Basic EPS:
Net income (loss) attributable to AGL	$	881	$	1,056	1,088
Less: Distributed and undistributed income (loss) available to nonvested shareholders	1		1		0
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	880	$	1,055	1,088
Basic shares	133.0		148.1		172.6
Basic EPS	$	6.61	$	7.12	$	6.30
Diluted EPS:
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	880	$	1,055	$	1,088
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	$	880	$	1,055	$	1,088
Basic shares	133.0		148.1		172.6
Dilutive securities	1.1		0.9		1.0
Diluted shares	134.1		149.0		173.6
Diluted EPS	$	6.56	$	7.08	$	6.26
Potentially dilutive securities excluded from computation of EPS because of antidilutive effect	0.3		0.5		1.6

Schedule of antidilutive securities excluded from computation of earnings per share

Computation of Earnings Per Share

	Year Ended December 31,
	2016		2015		2014
	(in millions, except per share amounts)
Basic EPS:
Net income (loss) attributable to AGL	$	881	$	1,056	1,088
Less: Distributed and undistributed income (loss) available to nonvested shareholders	1		1		0
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	880	$	1,055	1,088
Basic shares	133.0		148.1		172.6
Basic EPS	$	6.61	$	7.12	$	6.30
Diluted EPS:
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	880	$	1,055	$	1,088
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	$	880	$	1,055	$	1,088
Basic shares	133.0		148.1		172.6
Dilutive securities	1.1		0.9		1.0
Diluted shares	134.1		149.0		173.6
Diluted EPS	$	6.56	$	7.08	$	6.26
Potentially dilutive securities excluded from computation of EPS because of antidilutive effect	0.3		0.5		1.6