Fair Value Measurements (Narratives) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($) Investments	Dec. 31, 2015 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate fund investments	$ 519,386	$ 574,761
Real estate fund investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number Of Investments Held By Fund | Investments	6
Real estate fund investments	$ 519,386
Excess of fair value over cost	$ 210,451
Real estate fund investments | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Anticipated Investment Holding Period	1 year
Real estate fund investments | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Anticipated Investment Holding Period	4 years 4 months