Common Stock and Earnings Per Share (Details Textuals) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions		1 Months Ended	12 Months Ended
	Oct. 01, 2019	Nov. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Issuance of common stock		$ 339	$ 1,023	$ 0	$ 0
Shares issued in conjunction with acquisition of Blue Union and LEAP (in shares)		2,760
Price per share (in dollars per share)		$ 126.00
Gross value of shares issued in conjunction with acquisition of Blue Union and LEAP		$ 348
Stock Repurchase Contract, 2016 Series C Equity Units Subject to Mandatory Redemption
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Shares of common stock issued under stock repurchase contracts (in shares)	5,870
Issuance of common stock	$ 675