Employee Benefit Plans (Details 2) (United Kingdom Defined Benefit Pension Plans)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Target range of asset allocation
Weighted average asset allocation (as a percent)	100.00%	100.00%
Equity securities
Target range of asset allocation
Target range of asset allocation, minimum (as a percent)	40.00%
Target range of asset allocation, maximum (as a percent)	50.00%
Weighted average asset allocation (as a percent)	46.00%	48.00%
Debt securities
Target range of asset allocation
Target range of asset allocation, minimum (as a percent)	40.00%
Target range of asset allocation, maximum (as a percent)	50.00%
Weighted average asset allocation (as a percent)	46.00%	42.00%
Real estate
Target range of asset allocation
Target range of asset allocation, minimum (as a percent)	5.00%
Target range of asset allocation, maximum (as a percent)	10.00%
Weighted average asset allocation (as a percent)	5.00%	5.00%
Other
Target range of asset allocation
Target range of asset allocation, minimum (as a percent)	0.00%
Target range of asset allocation, maximum (as a percent)	5.00%
Weighted average asset allocation (as a percent)	3.00%	5.00%