Commitments and Contingencies (Details) (USD $) In Millions	6 Months Ended
	Jun. 30, 2011 Japan, New Zealand & United States [Member] Catastrophe exposure [Member]	Jun. 30, 2010 Chilean Earthquake [Member] Catastrophe exposure [Member]	Jun. 30, 2011 Indemnification Agreement [Member]
Commitments and Contingencies [Line Items]
Recognized Gross losses from catastrophic events	$ 120.3	$ 31.9
Liability related to indemnifications			9.5
Pretax loss after reinsurance	73.3	20.6
Letters of credit to cover obligations or anticipated payments			5.2
Amount in escrow account			$ 3.0