Borrowings and Lines of Credit Borrowings and lines of Credit (Current Year Actions) (Details) € in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018 USD ($)	Dec. 31, 2018 EUR (€)
Debt Instrument [Line Items]
Proceeds from Issuance of Debt			$ 11,000
Average Years of Maturity of Long Term Debt	11 years
Average interest expense rate	3.60%	3.40%
Notes 3.350% Due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.35%
Debt Instrument, Maturity Date, Description	2021
Debt Instrument, Issuance Date			Aug. 16, 2018	Aug. 16, 2018
Proceeds from Issuance of Debt			$ 1,000
Notes 3.650% Due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.65%
Debt Instrument, Maturity Date, Description	2023
Debt Instrument, Issuance Date			Aug. 16, 2018	Aug. 16, 2018
Proceeds from Issuance of Debt			$ 2,250
Notes 3.950% Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.95%
Debt Instrument, Maturity Date, Description	2025
Debt Instrument, Issuance Date			Aug. 16, 2018	Aug. 16, 2018
Proceeds from Issuance of Debt			$ 1,500
Notes 4.125% Due 2028 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.125%
Debt Instrument, Maturity Date, Description	2028
Debt Instrument, Issuance Date			Aug. 16, 2018	Aug. 16, 2018
Proceeds from Issuance of Debt			$ 3,000
Notes 4.450% Due 2038 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.45%
Debt Instrument, Maturity Date, Description	2038
Debt Instrument, Issuance Date			Aug. 16, 2018	Aug. 16, 2018
Proceeds from Issuance of Debt			$ 750
Notes 4.625% Due 2048 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.625%
Debt Instrument, Maturity Date, Description	2048
Debt Instrument, Issuance Date			Aug. 16, 2018	Aug. 16, 2018
Proceeds from Issuance of Debt			$ 1,750
LIBOR plus 0.650% floating rate notes due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date, Description	2021
Debt Instrument, Issuance Date			Aug. 16, 2018	Aug. 16, 2018
Proceeds from Issuance of Debt			$ 750
Notes 1.150% Due 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.15%
Debt Instrument, Maturity Date, Description	2024
Debt Instrument, Issuance Date			May 18, 2018	May 18, 2018
Proceeds from Issuance of Debt | €				€ 750
Notes 2.150% Due 2030 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	2.15%
Debt Instrument, Maturity Date, Description	2030
Debt Instrument, Issuance Date			May 18, 2018	May 18, 2018
Proceeds from Issuance of Debt | €				€ 500
EURIBOR plus 0.20% floating rate notes due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date, Description	2020
Debt Instrument, Issuance Date			May 18, 2018	May 18, 2018
Proceeds from Issuance of Debt | €				€ 750
Variable-rate term loan due 2020 (1 month LIBOR plus 1.25%) [Member]
Debt Instrument [Line Items]
Repayment of Debt, Date			Dec. 14, 2018	Dec. 14, 2018
Repayments of Debt			$ 482
Junior subordinated notes 1.778% due 2018 [Member]
Debt Instrument [Line Items]
Repayment of Debt, Date			May 04, 2018	May 04, 2018
Repayments of Debt			$ 1,100
EURIBOR plus 0.800% floating rate notes due 2018 [Member]
Debt Instrument [Line Items]
Repayment of Debt, Date			Feb. 22, 2018	Feb. 22, 2018
Repayments of Debt | €				€ 750
Notes 6.800% Due 2018 [Member]
Debt Instrument [Line Items]
Repayment of Debt, Date			Feb. 01, 2018	Feb. 01, 2018
Repayments of Debt			$ 99