Fair Value Measurements (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Real Estate Fund [Member]
Unobservable Quantitative Input [Abstract]
Beginning balance	$ 566,696	$ 554,426	$ 574,761	$ 513,973	$ 513,973
Purchases	0	0	0	95,000
Sales/Dispositions/distributions	(57,212)	(11,235)	(71,888)	(83,421)
Net unrealized gains	14,666	23,332	20,855	39,545
Net realized gains	0	886	422	2,312
Other, net	0	(1,433)	0	(1,433)
Ending balance	524,150	565,976	$ 524,150	565,976	$ 574,761
Real Estate Fund [Member] | Minimum [Member]
Unobservable Quantitative Input [Abstract]
Discount rates			12.00%		12.00%
Capitalization rate			4.80%		4.80%
Real Estate Fund [Member] | Maximum [Member]
Unobservable Quantitative Input [Abstract]
Discount rates			14.90%		14.90%
Capitalization rate			6.10%		6.10%
Real Estate Fund [Member] | Weighted Average [Member]
Unobservable Quantitative Input [Abstract]
Discount rates			13.70%		13.60%
Capitalization rate			5.50%		5.50%
Deferred Compensation Plan Assets [Member]
Unobservable Quantitative Input [Abstract]
Beginning balance	57,184	64,836	$ 59,186	63,315	$ 63,315
Purchases	1,106	5,607	2,272	6,231
Sales/Dispositions/distributions	(779)	(4,655)	(2,151)	(5,093)
Realized and unrealized gain	2,219	1,387	312	2,722
Other, net	410	493	521	493
Ending balance	$ 60,140	$ 67,668	$ 60,140	$ 67,668	$ 59,186