Segment Information - Narrative (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) segments		Mar. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of segments | segments	2
Net results from structured products	$ 2,914	[1]	$ 1,970	[2]
Net investment income | Total P&C
Segment Reporting Information [Line Items]
Net results from structured products	13,400		12,700
Interest Expense [Member] | Total P&C
Segment Reporting Information [Line Items]
Net results from structured products	$ (10,500)		$ (10,700)

[1] The net results from P&C structured products include net investment income and interest expense of $13.4 million and $10.5 million, respectively.

[2] The net results from P&C structured products include net investment income and interest expense of $12.7 million and $10.7 million, respectively.