Retirement and Other Postretirement Benefit Plans - Schedule of Actual Allocations for the Pension Assets and Target Allocations by Asset Class (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Change in plan assets:
Total plan assets invested in active corporate bond funds (as a percent)	100.00%	100.00%
Target allocations by asset class (as a percent)	100.00%	100.00%
Diversified Growth Funds
Change in plan assets:
Total plan assets invested in active corporate bond funds (as a percent)	27.60%
Target allocations by asset class (as a percent)	32.00%
Liability Driven Investments
Change in plan assets:
Total plan assets invested in active corporate bond funds (as a percent)	23.40%
Target allocations by asset class (as a percent)	20.00%
All Other Regions Equity Fund
Change in plan assets:
Total plan assets invested in active corporate bond funds (as a percent)	19.50%	27.70%
Target allocations by asset class (as a percent)	23.00%	30.60%
U.K. Equity Fund
Change in plan assets:
Total plan assets invested in active corporate bond funds (as a percent)	13.00%	28.10%
Target allocations by asset class (as a percent)	15.00%	30.60%
Debt Securities
Change in plan assets:
Total plan assets invested in active corporate bond funds (as a percent)	8.90%	39.20%
Target allocations by asset class (as a percent)	10.00%	34.50%
Index Linked Gilts
Change in plan assets:
Total plan assets invested in active corporate bond funds (as a percent)	3.70%
Diversified Investment, Funds
Change in plan assets:
Total plan assets invested in active corporate bond funds (as a percent)	2.00%	1.90%
Target allocations by asset class (as a percent)		1.90%
Other Insurance Product Line
Change in plan assets:
Total plan assets invested in active corporate bond funds (as a percent)	1.50%	2.40%
Target allocations by asset class (as a percent)		2.40%
Cash and Cash Equivalents
Change in plan assets:
Total plan assets invested in active corporate bond funds (as a percent)	0.40%	0.70%