Marketable Securities and Derivative Instruments: Marketable Securities (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended					0 Months Ended		3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Lexington Realty Trust [Member]	Dec. 31, 2012 Lexington Realty Trust [Member]	Sep. 19, 2013 JC Penney [Member]	Mar. 04, 2013 JC Penney [Member]	Mar. 31, 2013 JC Penney [Member]	Dec. 31, 2013 JC Penney [Member]	Dec. 31, 2012 JC Penney [Member]	Dec. 31, 2013 Other Equity Securities [Member]	Dec. 31, 2012 Other Equity Securities [Member]
Available-for-sale Securities, Gross Realized Gain (Loss), Disclosures [Abstract]
Available-for-sale Securities, Gross Realized Gain (Loss)						$ (18,114)	$ (36,800)
Schedule of Available-for-sale Securities [Line Items]
Non-cash impairment loss on J.C. Penney common shares	39,487	224,937	0					39,487
Available-for-sale Securities, Equity Securities	191,917	398,188		188,567	0				0	366,291	3,350	31,897
Marketable securities	191,917	398,188
Available-for-sale Equity Securities, Amortized Cost Basis	72,608	378,756		72,549	0				0	366,291	59	12,465
Available-for-sale Securities, Gross Unrealized Gain (Loss)	$ 119,309	$ 19,432		$ 116,018	$ 0				$ 0	$ 0	$ 3,291	$ 19,432