Credit Facilities and Long-Term Debt (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014	Sep. 20, 2011
Credit Facilities and Long-Term Debt :
Debt issuance costs and unamortized discount	$ (4,000,000)	$ (5,000,000)
Total debt	1,274,000,000	1,284,000,000
Short-term Debt	78,000,000	89,000,000
Long-term debt	1,196,000,000	1,195,000,000
Senior Notes Due 2016, 3.550%
Debt Instrument
Debt Instrument, Face Amount	600,000,000	600,000,000	$ 600,000,000
Other Long Term Debt
Credit Facilities and Long-Term Debt :
Senior Notes Due	2,000,000	5,000,000
Senior Notes Due 2021, 4.875%
Debt Instrument
Debt Instrument, Face Amount	600,000,000	600,000,000	$ 600,000,000
Research and Development Facility Agreement
Credit Facilities and Long-Term Debt :
Senior Notes Due	$ 76,000,000	$ 84,000,000