Variable Interest Entities and Noncontrolling Interests - Non-redeemable noncontrolling interests (Details) (USD $) In Thousands, unless otherwise specified							3 Months Ended
	Mar. 31, 2014		Dec. 31, 2013		Mar. 31, 2013		Mar. 31, 2014 Watford Holdings Ltd Noncontrolling Interest		Mar. 31, 2014 Common shares Watford Holdings Ltd Noncontrolling Interest
Noncontrolling Interest [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners									89.00%
Non-redeemable noncontrolling interests, beginning of year	$ 793,496	[1]	$ 0	[1]	$ 0	[1]	$ 0	[1]
Sale of shares to noncontrolling interests							796,903
Net (loss) income attributable to noncontrolling interests							(3,407)
Non-redeemable noncontrolling interests, end of period	$ 793,496	[1]	$ 0	[1]	$ 0	[1]	$ 793,496	[1]

[1] See Note 4.