Fair Value Measurements (Narratives) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015 Investments	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate fund investments	$ 554,426	$ 513,973
Real Estate Fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number Of Investments Held By Fund	6
Real estate fund investments	554,426
Excess of fair value over cost	$ 169,832
Real Estate Fund [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Anticipated Investment Holding Period	0 years 9 months 18 days
Real Estate Fund [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Anticipated Investment Holding Period	5 years 9 months 18 days