Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Schedule of computation of basic and diluted earnings per share

Computation of Earnings Per Share 

	Year Ended December 31,
	2021		2020		2019
	(in millions, except per share amounts)
Basic EPS:
Net income (loss) attributable to AGL	$	389	$	362	402
Less: Distributed and undistributed income (loss) available to nonvested shareholders	—		1		1
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	389	$	361	401
Basic shares	73.5		85.5		99.3
Basic EPS	$	5.29	$	4.22	$	4.04
Diluted EPS:
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	389	$	361	$	401
Plus: Re-allocation of undistributed income (loss) available to nonvested shareholders of AGL and subsidiaries	—		—		—
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, diluted	$	389	$	361	$	401
Basic shares	73.5		85.5		99.3
Dilutive securities:
Options and restricted stock awards	0.8		0.7		0.9
Diluted shares	74.3		86.2		100.2
Diluted EPS	$	5.23	$	4.19	$	4.00
Potentially dilutive securities excluded from computation of EPS because of antidilutive effect	0.1		0.8		—

Schedule of antidilutive securities excluded from computation of earnings per share

Computation of Earnings Per Share 

	Year Ended December 31,
	2021		2020		2019
	(in millions, except per share amounts)
Basic EPS:
Net income (loss) attributable to AGL	$	389	$	362	402
Less: Distributed and undistributed income (loss) available to nonvested shareholders	—		1		1
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	389	$	361	401
Basic shares	73.5		85.5		99.3
Basic EPS	$	5.29	$	4.22	$	4.04
Diluted EPS:
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	389	$	361	$	401
Plus: Re-allocation of undistributed income (loss) available to nonvested shareholders of AGL and subsidiaries	—		—		—
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, diluted	$	389	$	361	$	401
Basic shares	73.5		85.5		99.3
Dilutive securities:
Options and restricted stock awards	0.8		0.7		0.9
Diluted shares	74.3		86.2		100.2
Diluted EPS	$	5.23	$	4.19	$	4.00
Potentially dilutive securities excluded from computation of EPS because of antidilutive effect	0.1		0.8		—