Funds Held - Directly Managed Maturity Profile - (Details) (Funds held directly managed [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2014
Cost [Member]
Maturity Profile [Line Items]
One year or less	$ 75,985
More than one year through five years	230,696
More than five years through ten years	131,917
More than ten years	287
Total	438,885
Fair value [Member]
Maturity Profile [Line Items]
One year or less	76,822
More than one year through five years	241,496
More than five years through ten years	140,644
More than ten years	233
Total	$ 459,195