Marketable Securities and Derivative Instruments: Marketable Securities (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended							3 Months Ended	12 Months Ended
	Mar. 31, 2011	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 JC Penney [Member]	Dec. 31, 2011 JC Penney [Member]	Mar. 31, 2012 Other Equity Securities [Member]	Dec. 31, 2011 Other Equity Securities [Member]	Mar. 31, 2012 Debt Securities [Member]	Dec. 31, 2011 Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Equity Securities				$ 658,431	$ 653,228	$ 36,503	$ 29,544
Available-for-sale Securities, Debt Securities								59,576	58,549
Marketable Securities, Total		754,510	741,321
Available-for-sale Equity Securities, Amortized Cost Basis				591,069	591,069	13,561	13,561
Available-for-sale Debt Securities, Amortized Cost Basis								55,460	54,965
Available For Sale Securities Amortized Cost		660,090	659,595
Aggregate unrealized gains		94,420	81,726	67,362	62,159	22,942	15,983	4,116	3,584
Available-for-sale Securities, Debt Maturity, Date Range, Low								04/13	04/13
Available-for-sale Securities, Debt Maturity, Date Range, High								10/18	10/18
Available-for-sale Securities, Gross Realized Gain (Loss), Disclosures [Abstract]
Available For Sale Securities Gross Realized Gains Losses Sale Proceeds	15,162
Available For Sale Securities Gross Realized Gains	$ 2,091