Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2018

Stockholders' Equity Note [Abstract]

Schedule of Accelerated Share Repurchases

During the years ended December 31, 2018 and 2017, the Company entered into and completed ASR Agreements and open-market repurchases as presented below:

millions except per-share amounts
Agreement Date	Settlement Date	Amount		Average Price per Share			Initial Shares Delivered	Additional Shares Delivered	Total Shares Delivered
ASR Agreements
October 2017	December 2017	$	1,000		$	48.13	15.7	5.1	20.8
January 2018	February 2018	500			58.82		7.0	1.5	8.5
March 2018	June 2018	1,441			65.28		19.1	3.0	22.1
Total ASR Agreements		2,941					41.8	9.6	51.4
Open-market repurchases
December 2017	December 2017	59			52.00		N/A	N/A	1.1
August 2018	August 2018	250			66.14		N/A	N/A	3.8
September 2018	September 2018	250			63.11		N/A	N/A	3.9
December 2018	December 2018	250			52.34		N/A	N/A	4.8
Total open-market repurchases		809							13.6
Total		$	3,750		$	57.69			65.0

Common Stock Rollforward

The following summarizes the changes in the Company’s outstanding shares of common stock:

millions	2018	2017	2016
Shares of common stock issued
Shares at January 1	574	572	528
Exercise of stock options	—	—	1
Issuance of common stock	—	—	41
Issuance of restricted stock	3	2	2
Shares at December 31	577	574	572
Shares of common stock held in treasury
Shares at January 1	43	21	20
Purchase of treasury stock	43	22	—
Shares received for restricted stock vested and stock options exercised	1	—	1
Shares at December 31	87	43	21
Shares of common stock outstanding at December 31	490	531	551

Earnings Per Share Table

The following provides a reconciliation between basic and diluted EPS attributable to common stockholders for the years ended December 31:

millions except per-share amounts	2018			2017			2016
Net income (loss)
Net income (loss) attributable to common stockholders	$	615		$	(456	)	$	(3,071	)
Income (loss) effect of TEUs	(4		)	(7		)	(6		)
Less distributions on participating securities	5			1			1
Basic	$	606		$	(464	)	$	(3,078	)
Income (loss) effect of TEUs	(1		)	(2		)	(1		)
Diluted	$	605		$	(466	)	$	(3,079	)
Shares
Average number of common shares outstanding—basic	504			548			522
Average number of common shares outstanding—diluted	504			548			522
Excluded due to anti-dilutive effect	9			11			11
Net income (loss) per common share
Basic	$	1.20		$	(0.85	)	$	(5.90	)
Diluted	$	1.20		$	(0.85	)	$	(5.90	)
Dividends per common share	$	1.05		$	0.20		$	0.20