Marketable Securities and Derivative Instruments: Derivative Instrument (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Derivative [Line Items]
Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax	$ 18,358	$ (161,178)	$ (202,167)	$ (120,334)
Derivative Instrument That Does Not Qualify For Hedge Accounting [Abstract]
Derivative Basis Spread On Variable Rate	0.80%		0.80%
Payments to fund derivative collateral			121,117	33,850
JC Penney [Member]
Derivative [Line Items]
Investment Owned Balance Shares	23,400,000		23,400,000
Ownership Percentage	10.70%		10.70%
Closing share price	$ 24.29		$ 24.29
Economic Gain	(20,667)		(20,667)
Economic Cost Per Share	$ 26.43		$ 26.43
JC Penney [Member] | Derivative [Member]
Derivative Instrument That Does Not Qualify For Hedge Accounting [Abstract]
Derivative Number Of Instruments Held	4,815,990		4,815,990
Derivative Maturity Date			Oct. 08, 2022
Derivative Price Risk Option Strike Price	$ 29.01		$ 29.01
Notional Amount Of Price Risk Derivatives	139,723		139,723
Derivative Basis Spread On Variable Rate	0.95%		0.95%
Derivative Gain On Derivative	4,344	(37,537)	(53,343)	(27,136)
Payments to fund derivative collateral			31,267
Derivative Amended Date			Oct. 08, 2012
Derivative Earliest Settlement Date			Oct. 08, 2014
Derivative Term			2 years
JC Penney [Member] | Available-for-sale Securities [Member]
Derivative [Line Items]
Investment Owned Balance Shares	18,584,010		18,584,010
Acquisiton Price Per Share			$ 25.76
Investment Owned, at Cost	478,677		478,677
Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax	18,213	(144,212)	(201,967)	(102,920)
Investment Owned At Fair Value	$ 451,406		$ 451,406