Retirement Plans and Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Amounts were included in the statement of income as follows:
Income from continuing operations	$ 459	$ 464
Income (loss) from discontinued operations	(105)	22
Net periodic benefit cost	354	486
Pension [Member]
Components of net periodic benefit cost:
Service cost	23	25
Interest cost	24	28
Expected return on plan assets	(39)	(40)
Amortization of actuarial loss	19	13
Amortization of prior service cost	0	0
Net periodic benefit cost	27	26
Amounts were included in the statement of income as follows:
Income from continuing operations	27	25
Income (loss) from discontinued operations	0	1
Net periodic benefit cost	27	26
Other Postretirement Benefits [Member]
Components of net periodic benefit cost:
Service cost	3	3
Interest cost	6	7
Expected return on plan assets	(5)	(5)
Amortization of actuarial loss	0	0
Amortization of prior service cost	0	1
Net periodic benefit cost	4	6
Amounts were included in the statement of income as follows:
Income from continuing operations	4	6
Income (loss) from discontinued operations	0	0
Net periodic benefit cost	$ 4	$ 6