Accounting Policies New Accounting Pronouncements (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets	$ 1,443	$ 1,445
Assets	74,668	74,187
Long-term debt	11,633	11,630
Total liabilities and shareholders’ equity	74,668	74,187
Long-term Debt [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reductions in Other Assets and Long-Term Debt, Amount	(60)	65
Long-term Debt [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reductions in Other Assets and Long-Term Debt, Amount	$ 60	65
Scenario, Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets		(65)
Assets		(65)
Long-term debt		(65)
Total liabilities and shareholders’ equity		(65)
Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets		1,510
Assets		74,252
Long-term debt		11,695
Total liabilities and shareholders’ equity		$ 74,252