Fair Value Measurements (Details 1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Real Estate Fund [Member]
Unobservable Quantitative Input [Abstract]
Beginning balance	$ 565,976	$ 549,091	$ 513,973	$ 667,710	$ 667,710
Purchases	11	725	95,011	3,392
Sales/Dispositions/distributions	(8,029)	(74,755)	(91,450)	(307,268)
Net unrealized (losses) gains	(2,544)	18,333	37,001	55,221
Net realized (losses) gains	(907)	1,998	1,405	76,337
Other, net	907	0	(526)	0
Ending balance	555,414	495,392	$ 555,414	495,392	$ 513,973
Real Estate Fund [Member] | Minimum [Member]
Unobservable Quantitative Input [Abstract]
Discount rates			12.00%		12.00%
Capitalization rate			4.80%		4.70%
Real Estate Fund [Member] | Maximum [Member]
Unobservable Quantitative Input [Abstract]
Discount rates			14.50%		17.50%
Capitalization rate			6.50%		6.50%
Real Estate Fund [Member] | Weighted Average [Member]
Unobservable Quantitative Input [Abstract]
Discount rates			13.20%		13.70%
Capitalization rate			5.50%		5.30%
Deferred Compensation Plan Assets [Member]
Unobservable Quantitative Input [Abstract]
Beginning balance	67,668	64,609	$ 63,315	68,782	$ 68,782
Purchases	2,153	1,377	8,384	10,936
Sales/Dispositions/distributions	(171)	(4,917)	(5,264)	(21,296)
Realized and unrealized (loss) gain	(1,466)	927	1,256	2,901
Other, net	24	1,187	517	1,860
Ending balance	$ 68,208	$ 63,183	$ 68,208	$ 63,183	$ 63,315