Other Income (Expense) - Summary (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investment Income, Net [Abstract]
Interest and dividend income	$ 16,380	$ 6,602	$ 6,940
Accretion income	1,983	1,829	1,526
Net realized gain on the sale of investments	10,750	795	5,311
Other-than-temporary impairment loss	(2,288)	0	0
Total net investment income from available-for-sale securities	26,825	9,226	13,777
Interest income from investments in SPEs	8,201	8,202	8,217
Interest accrued on notes receivable and other interest	384	348	694
Total investment income, net	35,410	17,776	22,688
Interest expense
Interest expense and amortization of discount and issuance costs for Senior Notes issued by SPE	(8,777)	(8,833)	(8,755)
Other interest expense	(3,368)	(3,462)	(2,674)
Total interest expense	(12,145)	(12,295)	(11,429)
Claim settlement	0	12,548	0
Sale of vacation rental management, net	9,800	0	0
Other income (expense), net
Accretion income from retained interest investments	1,100	991	913
Hunting lease income	569	553	562
Miscellaneous income (expense), net	4,286	1,078	(7,762)
Other income (expense), net	5,955	2,622	(6,287)
Total other income, net	$ 39,020	$ 20,651	$ 4,972