Earnings Per Share (Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share) (Details) - shares shares in Millions |
3 Months Ended | |
---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
Securities excluded from computation of earnings per share (in shares) | 2 | |
Anti-dilutive share based awards | ||
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
Securities excluded from computation of earnings per share (in shares) | 16 | 9 |
PRSUs | ||
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
Securities excluded from computation of earnings per share (in shares) | 2 | 1 |