Real Estate Fund Investments - Schedule of Income from Fund Investment (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	$ (1,254)	$ (2,540)
Property Fund II [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	681	(32,578)
Property Fund VII [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	(4,083)	7,650
Property Fund III [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	602	(10,264)
Investment Income [Member] | Property Fund II [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	1,389	1,391
Investment Income [Member] | Property Fund VII [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	1,233	1,233
Investment Income [Member] | Property Fund III [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	480	480
Investment Expenses [Member] | Property Fund II [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	668	2,051
Investment Expenses [Member] | Property Fund VII [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	501	1,512
Investment Expenses [Member] | Property Fund III [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	55	193
Net investment income (loss) [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	170	(437)
Net investment income (loss) [Member] | Property Fund II [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	721	(660)
Net investment income (loss) [Member] | Property Fund VII [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	732	(279)
Net investment income (loss) [Member] | Property Fund III [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	425	287
Net Unrealized (Losses) Gains [Member] | Property Fund II [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	(40)	(31,918)
Net Unrealized (Losses) Gains [Member] | Property Fund VII [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	(4,815)	7,929
Net Unrealized (Losses) Gains [Member] | Property Fund III [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	$ 177	$ (10,551)