Pension and Postretirement Benefits other than Pensions Weighted Average Asset Allocations by Asset Category (Details)	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
US Penson Plan, Actual Plan Asset Allocations	100.00%	100.00%
United Kingdom Penson Plan, Actual Plan Asset Allocations	100.00%	100.00%
Germany Penson Plan, Actual Plan Asset Allocations	100.00%	100.00%
Equity Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
US Penson Plan, Actual Plan Asset Allocations	62.00%	62.00%
United Kingdom Penson Plan, Actual Plan Asset Allocations	32.00%	42.00%
Germany Penson Plan, Actual Plan Asset Allocations	14.00%	9.00%
Fixed Income Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
US Penson Plan, Actual Plan Asset Allocations	37.00%	37.00%
United Kingdom Penson Plan, Actual Plan Asset Allocations	67.00%	57.00%
Germany Penson Plan, Actual Plan Asset Allocations	80.00%	85.00%
Other Investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
US Penson Plan, Actual Plan Asset Allocations	1.00%	1.00%
United Kingdom Penson Plan, Actual Plan Asset Allocations	1.00%	1.00%
Germany Penson Plan, Actual Plan Asset Allocations	6.00%	6.00%