Fair Value Measurements - Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Total Fair Value Inputs [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Large Capitalization Registered Investment Companies	$ 370	$ 405
Mid Capitalization Registered Investment Companies	103	109
Small Capitalization Registered Investment Companies	87	95
International Developed And Emerging Markets Registered Investment Companies	190	205
Fixed Income Registered Investment Companies	40	43
Fixed General Account	155	167
Acquisition-related Consideration	4,830	4,876
Liabilities, Fair Value Disclosure	5,775	5,900
Fair Value, Inputs, Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Large Capitalization Registered Investment Companies	370	405
Mid Capitalization Registered Investment Companies	103	109
Small Capitalization Registered Investment Companies	87	95
International Developed And Emerging Markets Registered Investment Companies	190	205
Fixed Income Registered Investment Companies	40	43
Fixed General Account	0	0
Acquisition-related Consideration	0	0
Liabilities, Fair Value Disclosure	790	857
Fair Value, Inputs, Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Large Capitalization Registered Investment Companies	0	0
Mid Capitalization Registered Investment Companies	0	0
Small Capitalization Registered Investment Companies	0	0
International Developed And Emerging Markets Registered Investment Companies	0	0
Fixed Income Registered Investment Companies	0	0
Fixed General Account	155	167
Acquisition-related Consideration	0	0
Liabilities, Fair Value Disclosure	155	167
Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Large Capitalization Registered Investment Companies	0	0
Mid Capitalization Registered Investment Companies	0	0
Small Capitalization Registered Investment Companies	0	0
International Developed And Emerging Markets Registered Investment Companies	0	0
Fixed Income Registered Investment Companies	0	0
Fixed General Account	0	0
Acquisition-related Consideration	4,830	4,876
Liabilities, Fair Value Disclosure	$ 4,830	$ 4,876