Derivative Instruments - Narrative (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Dec. 31, 2013
Derivative [Line Items]
Gross amounts not offset in the balance sheet - cash collateral	$ 35,490				$ 35,490				$ 0
Collateral posted to counterparty	0				0				19,847
Net results from structured products	5,291		6,463		48,129		17,692
Fair value hedges | Deposit liabilities
Derivative [Line Items]
Remaining balance	140,153		199,816		140,153		199,816
Total P&C
Derivative [Line Items]
Net results from structured products	5,291	[1]	6,463	[2]	48,129	[3]	17,692	[4]
Total P&C | Interest expense
Derivative [Line Items]
Net results from structured products	(11,100)		(11,600)		(3,700)		(36,200)
Structured Indemnity [Member] | Fair value hedges | Deposit liabilities
Derivative [Line Items]
Remaining balance	47,000				47,000
Structured Indemnity [Member] | Total P&C | Interest expense
Derivative [Line Items]
Net results from structured products					28,700
Life Funds Withheld Assets
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	$ (172,077)		$ 0		$ (189,623)		$ 0

[1] The net results from structured products include net investment income and interest expense of $16.8 million and $11.1 million, respectively.

[2] The net results from structured products include net investment income and interest expense of $18.1 million and $11.6 million, respectively.

[3] The net results from structured products include net investment income and net interest expense of $52.5 million and $3.7 million, respectively. Net results from structured products includes a benefit of $28.7 million from a negotiated termination of one of the Company's larger structured indemnity contracts during the second quarter of 2014, producing a net interest expense credit.

[4] The net results from structured products include net investment income and interest expense of $53.9 million and $36.2 million, respectively.