Shareholders' Equity - Reclassification Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Reclassification out of Accumulated Other Comprehensive Income
Investment income	$ 26	$ 35	$ 51	$ 71
Product sales revenue	3,225	3,319	6,130	6,327
Cost of product sales	(1,433)	(1,372)	(2,762)	(2,668)
Other interest expense	(41)	(34)	(81)	(68)
Income (loss) before provision for income taxes	689	809	1,063	1,380
Income tax provision	170	187	252	326
Net income	519	622	811	1,054
Net gain on investments
Reclassification out of Accumulated Other Comprehensive Income
Income tax provision			31	61	$ 31	$ 18
Net gain on derivatives
Reclassification out of Accumulated Other Comprehensive Income
Income tax provision			(61)	(66)	(64)	(66)
Net gains from pension and other postretirement plans
Reclassification out of Accumulated Other Comprehensive Income
Income tax provision			(70)	(61)	$ (70)	$ (61)
Foreign Exchange Contract | Reclassification Out of Accumulated Other Comprehensive Income | Net gain on derivatives
Reclassification out of Accumulated Other Comprehensive Income
Product sales revenue	1	2	21	3
Cost of product sales	3	(1)	(1)	0
Income (loss) before provision for income taxes	(2)	1	9	3
Income tax provision	(2)	0	(2)	0
Net income	0	1	11	3
Interest Rate Swap | Reclassification Out of Accumulated Other Comprehensive Income | Net gain on interest rate swap
Reclassification out of Accumulated Other Comprehensive Income
Other interest expense	(6)	0	(11)	0
Unrealized Gain on Investments | Reclassification Out of Accumulated Other Comprehensive Income | Net gain on investments
Reclassification out of Accumulated Other Comprehensive Income
Investment income	20	9	34	17
Income tax provision	(7)	(3)	(13)	(6)
Net income	$ 13	$ 6	$ 21	$ 11