Marketable Securities and Derivative Instruments: Derivative Instrument (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Derivative [Line Items]
Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax	$ 12,693	$ 68,039
JC Penney [Member]
Derivative [Line Items]
Investment Owned Balance Shares	23,400,000
Ownership Percentage	11.00%
Closing share price	$ 35.43
Economic Gain	211,544
Economic Cost Per Share	$ 26.39
JC Penney [Member] | Derivative [Member]
Derivative Instrument That Does Not Qualify For Hedge Accounting [Abstract]
Derivative Number Of Instruments Held	4,815,990
Derivative Inception Date	Oct. 07, 2010
Derivative Maturity Date	Oct. 09, 2012
Derivative Price Risk Option Strike Price	$ 28.86
Notional Amount Of Price Risk Derivatives	138,986
Derivative Basis Spread On Variable Rate	0.80%
Derivative Gain On Derivative	1,045	17,163
JC Penney [Member] | Available-for-sale Securities [Member]
Derivative [Line Items]
Investment Owned Balance Shares	18,584,010
Acquisiton Price Per Share	$ 25.75
Investment Owned, at Cost	478,532
Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax	5,203	66,903
Investment Owned At Fair Value	$ 658,431