Marketable Securities and Derivative Instruments: Derivative Instruments (Narratives) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		0 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 04, 2013 JC Penney [Member]
Derivative [Line Items]
Sale of Stock, Number of Shares			10,000,000
Closing share price (in dollars per share)			$ 16.03
Proceeds from sales of marketable securities	$ 0	$ 160,300	$ 160,300
Net loss on sale of common shares in J.C Penney			$ (36,800)