v2.4.1.9
Selected Quarterly Data (Unaudited) (Details) (USD $)
In Millions, except Per Share data, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Selected Quarterly Data (Unaudited) [Abstract]                      
Operating revenues $ 6,153us-gaap_Revenues $ 6,182us-gaap_Revenues $ 6,015us-gaap_Revenues $ 5,638us-gaap_Revenues $ 5,630us-gaap_Revenues $ 5,573us-gaap_Revenues $ 5,470us-gaap_Revenues $ 5,290us-gaap_Revenues $ 23,988us-gaap_Revenues $ 21,963us-gaap_Revenues $ 20,926us-gaap_Revenues
Operating income 2,373us-gaap_OperatingIncomeLoss 2,330us-gaap_OperatingIncomeLoss 2,196us-gaap_OperatingIncomeLoss 1,854us-gaap_OperatingIncomeLoss 1,973us-gaap_OperatingIncomeLoss 1,962us-gaap_OperatingIncomeLoss 1,878us-gaap_OperatingIncomeLoss 1,633us-gaap_OperatingIncomeLoss 8,753us-gaap_OperatingIncomeLoss 7,446us-gaap_OperatingIncomeLoss 6,745us-gaap_OperatingIncomeLoss
Net income $ 1,431us-gaap_NetIncomeLoss $ 1,370us-gaap_NetIncomeLoss $ 1,291us-gaap_NetIncomeLoss $ 1,088us-gaap_NetIncomeLoss $ 1,174us-gaap_NetIncomeLoss $ 1,151us-gaap_NetIncomeLoss $ 1,106us-gaap_NetIncomeLoss $ 957us-gaap_NetIncomeLoss $ 5,180us-gaap_NetIncomeLoss $ 4,388us-gaap_NetIncomeLoss $ 3,943us-gaap_NetIncomeLoss
Net Income Per Share [Abstract]                      
Earnings per share - basic $ 1.62us-gaap_EarningsPerShareBasic $ 1.53us-gaap_EarningsPerShareBasic $ 1.43us-gaap_EarningsPerShareBasic $ 1.20us-gaap_EarningsPerShareBasic $ 1.28us-gaap_EarningsPerShareBasic $ 1.25us-gaap_EarningsPerShareBasic $ 1.19us-gaap_EarningsPerShareBasic $ 1.02us-gaap_EarningsPerShareBasic $ 5.77us-gaap_EarningsPerShareBasic $ 4.74us-gaap_EarningsPerShareBasic $ 4.17us-gaap_EarningsPerShareBasic
Earnings per share - diluted $ 1.61us-gaap_EarningsPerShareDiluted $ 1.53us-gaap_EarningsPerShareDiluted $ 1.43us-gaap_EarningsPerShareDiluted $ 1.19us-gaap_EarningsPerShareDiluted $ 1.27us-gaap_EarningsPerShareDiluted $ 1.24us-gaap_EarningsPerShareDiluted $ 1.18us-gaap_EarningsPerShareDiluted $ 1.02us-gaap_EarningsPerShareDiluted $ 5.75us-gaap_EarningsPerShareDiluted $ 4.71us-gaap_EarningsPerShareDiluted $ 4.14us-gaap_EarningsPerShareDiluted