Capital Transactions	12 Months Ended
Dec. 31, 2018
Equity [Abstract]
Capital Transactions	Capital Transactions Repurchase Programs On January 31, 2019, our Board of Directors authorized a stock repurchase program under which we are authorized to repurchase up to $1.5 billion of our common stock from February 14, 2019 until the earlier of February 13, 2021 and a determination by the Board of Directors to discontinue the repurchase program. On February 2, 2017, our Board of Directors authorized a stock repurchase program under which we were authorized to repurchase up to $1 billion of our common stock from February 13, 2017 through February 12, 2019. We did not repurchase any shares under this program. Dividends On February 12, 2019, our Board of Directors declared a cash dividend of $0.37 per common share. Such dividend is payable on May 9, 2019, to shareholders of record at the close of business on March 28, 2019. On February 8, 2018, our Board of Directors declared a cash dividend of $0.34 per common share. On May 9, 2018, we made an aggregate cash dividend payment of $259 million to shareholders of record at the close of business on March 30, 2018. On February 9, 2017, our Board of Directors declared a cash dividend of $0.30 per common share. On May 10, 2017, we made an aggregate cash dividend payment of $226 million to shareholders of record at the close of business on March 30, 2017. On May 26, 2017, we made related dividend equivalent payments of less than $1 million to certain holders of restricted stock units. On February 11, 2016, our Board of Directors declared a cash dividend of $0.26 per common share. On May 11, 2016, we made an aggregate cash dividend payment of $192 million to shareholders of record at the close of business on March 30, 2016. On May 27, 2016, we made related dividend equivalent payments of $3 million to certain holders of restricted stock units.

Capital Transactions

Repurchase Programs

On January 31, 2019, our Board of Directors authorized a stock repurchase program under which we are authorized to repurchase up to $1.5 billion of our common stock from February 14, 2019 until the earlier of February 13, 2021 and a determination by the Board of Directors to discontinue the repurchase program.

On February 2, 2017, our Board of Directors authorized a stock repurchase program under which we were authorized to repurchase up to $1 billion of our common stock from February 13, 2017 through February 12, 2019. We did not repurchase any shares under this program.

Dividends

On February 12, 2019, our Board of Directors declared a cash dividend of $0.37 per common share. Such dividend is payable on May 9, 2019, to shareholders of record at the close of business on March 28, 2019.

On February 8, 2018, our Board of Directors declared a cash dividend of $0.34 per common share. On May 9, 2018, we made an aggregate cash dividend payment of $259 million to shareholders of record at the close of business on March 30, 2018.

On February 9, 2017, our Board of Directors declared a cash dividend of $0.30 per common share. On May 10, 2017, we made an aggregate cash dividend payment of $226 million to shareholders of record at the close of business on March 30, 2017. On May 26, 2017, we made related dividend equivalent payments of less than $1 million to certain holders of restricted stock units.

On February 11, 2016, our Board of Directors declared a cash dividend of $0.26 per common share. On May 11, 2016, we made an aggregate cash dividend payment of $192 million to shareholders of record at the close of business on March 30, 2016. On May 27, 2016, we made related dividend equivalent payments of $3 million to certain holders of restricted stock units.