Investments - Other Investments, at Cost (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) contract	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) contract	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) contract
Other Investments [Line Items]
Other investments, at cost	$ 129,636,000		$ 129,636,000		$ 133,071,000
Amount of net investment income included in earnings attributable to investments in life settlements	$ 54,223,000	$ 34,655,000	$ 114,286,000	$ 65,072,000
Number of Contracts
0 – 1 year | contract	2		2		2
1 – 2 years | contract	3		3		4
2 – 3 years | contract	18		18		19
3 – 4 years | contract	16		16		14
4 – 5 years | contract	21		21		16
Thereafter | contract	187		187		221
Total | contract	247		247		276
Carrying Value
0 – 1 year	$ 436,000		$ 436,000		$ 417,000
1 – 2 years	2,725,000		2,725,000		3,032,000
2 – 3 years	25,556,000		25,556,000		24,072,000
3 – 4 years	14,855,000		14,855,000		9,695,000
4 – 5 years	9,882,000		9,882,000		9,025,000
Thereafter	76,182,000		76,182,000		86,830,000
Total	129,636,000		129,636,000		133,071,000
Face Value (Death Benefits)
0 – 1 year	700,000		700,000		700,000
1 – 2 years	4,500,000		4,500,000		5,000,000
2 – 3 years	53,900,000		53,900,000		39,123,000
3 – 4 years	30,328,000		30,328,000		20,932,000
4 – 5 years	22,759,000		22,759,000		22,457,000
Thereafter	432,601,000		432,601,000		491,499,000
Total	544,788,000		544,788,000		$ 579,711,000
Life Settlement Contracts, Investment Method, Premiums to be Paid, Fiscal Year Maturity [Abstract]
Life insurance premiums payable in 2017	17,500,000		17,500,000
Life insurance premiums payable in 2018	17,400,000		17,400,000
Life insurance premiums payable in 2019	17,500,000		17,500,000
Life insurance premiums payable in 2020	17,200,000		17,200,000
Life insurance premiums payable in 2021	$ 15,700,000		15,700,000
Life Settlements
Other Investments [Line Items]
Amount of net investment income included in earnings attributable to investments in life settlements			10,000,000	2,000,000
Impairment charges recognized in the period			$ 2,900,000	$ 0