Fair Value Disclosures (Details 3) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Schedule of fair value measurements of investments in certain entities that calculate net asset value per share
Other investments, at fair value	$ 37,609	$ 42,772
Other Investment Vehicles [Member]
Schedule of fair value measurements of investments in certain entities that calculate net asset value per share
Other investments, at fair value	37,105	42,261
EuroDekania [Member] | Other Investment Vehicles [Member]
Schedule of fair value measurements of investments in certain entities that calculate net asset value per share
Other investments, at fair value	2,103	2,370
Unfunded commitments
Redemption frequency
Redemption notice period
Star Asia [Member] | Other Investment Vehicles [Member]
Schedule of fair value measurements of investments in certain entities that calculate net asset value per share
Other investments, at fair value	32,299	37,358
Unfunded commitments
Redemption frequency
Redemption notice period
Tiptree Financial Partners L.P. [Member] | Other Investment Vehicles [Member]
Schedule of fair value measurements of investments in certain entities that calculate net asset value per share
Other investments, at fair value	2,703	2,533
Unfunded commitments
Redemption frequency
Redemption notice period