Debt - Narrative (Details)			12 Months Ended																																							0 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2014 Commercial Paper [Member] USD ($)	Dec. 31, 2013 Commercial Paper [Member] USD ($)	Dec. 31, 2014 Other [Member] USD ($)	Dec. 31, 2013 Other [Member] USD ($)	Dec. 31, 2014 Other [Member] 3.50% debt securities due September 2015 [Member]	Aug. 12, 2014 Other [Member] 3.50% notes due 2024 [Member] USD ($)	May 20, 2014 Other [Member] 3.50% notes due 2024 [Member] USD ($)	May 20, 2014 Other [Member] 4.60% notes due 2044 [Member] USD ($)	May 07, 2014 Other [Member] 2.875% notes due 2026 [Member] EUR (€)	May 07, 2014 Other [Member] 6.25% EUR 500 debt securities due July 2014 [Member]	Dec. 31, 2014 4.00% senior notes dues November 2023 [Member] USD ($)	Dec. 31, 2013 4.00% senior notes dues November 2023 [Member] USD ($)	Nov. 21, 2013 4.00% senior notes dues November 2023 [Member] USD ($)	Dec. 31, 2014 4.45% senior notes due May 2043 [Member] USD ($)	Dec. 31, 2013 4.45% senior notes due May 2043 [Member] USD ($)	May 21, 2013 4.45% senior notes due May 2043 [Member] USD ($)	Dec. 31, 2014 4.25% senior notes due December 2042 [Member] USD ($)	Dec. 31, 2013 4.25% senior notes due December 2042 [Member] USD ($)	Apr. 15, 2013 4.25% senior notes due December 2042 [Member] USD ($)	Mar. 08, 2013 4.25% senior notes due December 2042 [Member] USD ($)	Dec. 12, 2012 4.25% senior notes due December 2042 [Member] USD ($)	Dec. 31, 2014 8.205% junior subordinated deferrable interest debentures due January 2027 [Member] USD ($)	Dec. 31, 2013 8.205% junior subordinated deferrable interest debentures due January 2027 [Member] USD ($)	Dec. 31, 2012 8.205% junior subordinated deferrable interest debentures due January 2027 [Member]	Dec. 31, 2014 3.125% senior notes due May 2016 [Member] USD ($)	Dec. 31, 2013 3.125% senior notes due May 2016 [Member] USD ($)	Dec. 31, 2014 4.76% CAD 375 debt securities due March 2018 [Member] USD ($)	Dec. 31, 2014 4.76% CAD 375 debt securities due March 2018 [Member] CAD	Dec. 31, 2013 4.76% CAD 375 debt securities due March 2018 [Member] USD ($)	Dec. 31, 2014 3.50% senior notes due September 2015 [Member] USD ($)	Dec. 31, 2013 3.50% senior notes due September 2015 [Member] USD ($)	Dec. 31, 2014 5.00% Senior notes due September 2020 [Member] USD ($)	Dec. 31, 2013 5.00% Senior notes due September 2020 [Member] USD ($)	Dec. 31, 2014 6.25% Senior notes due September 2040 [Member] USD ($)	Dec. 31, 2013 6.25% Senior notes due September 2040 [Member] USD ($)	Dec. 31, 2014 6.25% EUR 500 debt securities due July 2014 [Member] USD ($)	Dec. 31, 2014 6.25% EUR 500 debt securities due July 2014 [Member] EUR (€)	Dec. 31, 2013 6.25% EUR 500 debt securities due July 2014 [Member] USD ($)	Dec. 31, 2014 Short-term debt and current portion of long-term debt [Member] 3.50% debt securities due September 2015 [Member] USD ($)	May 07, 2014 6.25% EUR 500 debt securities due July 2014 [Member] EUR (€)	Dec. 31, 2014 US Credit Facility [Member] Line of Credit [Member] 2017 Facility [Member] USD ($)	Dec. 31, 2014 European Credit Facility [Member] Line of Credit [Member] 2015 Facility [Member] USD ($)	Dec. 31, 2014 European Credit Facility [Member] Line of Credit [Member] 2015 Facility [Member] EUR (€)	Feb. 02, 2015 Subsequent Event [Member] European Credit Facility [Member] Line of Credit [Member] 2020 Facility [Member] EUR (€)	Dec. 31, 2014 Commercial Paper [Member] US Commercial Paper Program [Member] USD ($)	Dec. 31, 2014 Commercial Paper [Member] European Multi-Currency Commercial Paper Program [Member] EUR (€)
Debt Instrument [Line Items]
New credit and loan facility																																											$ 400,000,000	$ 792,000,000	€ 650,000,000	€ 900,000,000	$ 900,000,000	€ 300,000,000
Debt face value								350,000,000	250,000,000	550,000,000	500,000,000				350,000,000			250,000,000			256,000,000	90,000,000	166,000,000							375,000,000									500,000,000		600,000,000
Interest rate on debt							3.50%	3.50%	3.50%	4.60%	2.875%	6.25%	4.00%		4.00%	4.45%		4.45%	4.25%		4.25%	4.25%	4.25%	8.205%		8.205%	3.125%		4.76%	4.76%		3.50%		5.00%		6.25%		6.25%	6.25%
Extinguishment of debt																																										500,000,000
Total debt	5,582,000,000	4,389,000,000	168,000,000	0	31,000,000	43,000,000							349,000,000	349,000,000		248,000,000	248,000,000		196,000,000	195,000,000				521,000,000	521,000,000		500,000,000	500,000,000	322,000,000		352,000,000	599,000,000	599,000,000	599,000,000	599,000,000	298,000,000	298,000,000	0		685,000,000
Weighted average commercial paper outstanding			$ 308,000,000	$ 339,000,000
Weighted-average interest rates			0.35%	0.35%