Real Estate Fund Investments - Schedule of Income from Fund Investment (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	$ 1,412	$ (498)	$ 37,975
Property Fund II [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		(1,820)
Property Fund III [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		3,754
Property Fund VII [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		12,356
Investment Income [Member] | Property Fund II [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		2,780
Investment Income [Member] | Property Fund III [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		1,739
Investment Income [Member] | Property Fund VII [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		1,233
Investment Expenses [Member] | Property Fund II [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		2,694
Investment Expenses [Member] | Property Fund III [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		184
Investment Expenses [Member] | Property Fund VII [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		2,000
Net investment income (loss) [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	2,769	(324)	12,274
Net investment income (loss) [Member] | Property Fund II [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		86
Net investment income (loss) [Member] | Property Fund III [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		1,555
Net investment income (loss) [Member] | Property Fund VII [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		(767)
Net Unrealized (Losses) Gains [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments	$ (1,407)	(1,706)	$ 18,401
Net Unrealized (Losses) Gains [Member] | Property Fund II [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		(1,906)
Net Unrealized (Losses) Gains [Member] | Property Fund III [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		2,199
Net Unrealized (Losses) Gains [Member] | Property Fund VII [Member]
Investment Holdings [Line Items]
Income (loss) from real estate fund investments		$ 13,123