Shareholders' Equity - Reclassification Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Reclassification out of Accumulated Other Comprehensive Income
Investment income	$ 25	$ 29	$ 76	$ 100
Product sales revenue	3,269	3,400	9,399	9,728
Cost of product sales	(1,379)	(1,400)	(4,141)	(4,068)
Other interest expense	(41)	(40)	(121)	(108)
Income (loss) before provision for income taxes	696	833	1,759	2,213
Provision for income tax	(168)	(206)	(420)	(532)
Net income	528	627	1,339	1,681
Net gain on investments
Reclassification out of Accumulated Other Comprehensive Income
Provision for income tax			(8)	(72)	$ (31)	$ (18)
Net gain on derivatives
Reclassification out of Accumulated Other Comprehensive Income
Provision for income tax			58	63	64	66
Net gains from pension and other postretirement plans
Reclassification out of Accumulated Other Comprehensive Income
Provision for income tax			70	61	$ 70	$ 61
Reclassification Out of Accumulated Other Comprehensive Income | Net gains from pension and other postretirement plans
Reclassification out of Accumulated Other Comprehensive Income
Provision for income tax	0	0	0	0
Net income	0	1	0	1
Other Cost and Expense, Operating	0	1	0	(1)
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	12	22	15
Cost of product sales	0	(7)	(1)	(7)
Income (loss) before provision for income taxes	(5)	(1)	4	2
Provision for income tax	2	0	4	0
Net income	(3)	(1)	8	2
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)	(6)	(17)	(6)
Unrealized Gain on Investments | Reclassification Out of Accumulated Other Comprehensive Income | Net gain on investments
Reclassification out of Accumulated Other Comprehensive Income
Investment income	8	13	42	30
Provision for income tax	3	5	16	11
Net income	$ 5	$ 8	$ 26	$ 19