Investments Income from Equity Investments (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 29, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 28, 2014
Schedule of Equity Method Investments [Line Items]
Income from equity investments, net, before amortization of basis difference										$ 202,758	$ 201,207	$ 379,048
Amortization of basis difference	[1]									(54,602)	(54,248)	(142,335)
Income on equity investments, net		$ 33,861	$ 31,737	$ 44,306	$ 38,252	$ 27,125	$ 36,987	$ 45,913	$ 36,934	$ 148,156	$ 146,959	236,713
Apartments.com
Schedule of Equity Method Investments [Line Items]
Amortization of basis difference												$ (85,000)

[1] (1) Amortization of basis difference for the year ended December 28, 2014 includes $85 million related to the sale by CV of its Apartments.com business.