Capital Stock (Details) (USD $)	6 Months Ended	1 Months Ended	6 Months Ended		6 Months Ended		3 Months Ended			6 Months Ended								1 Months Ended	12 Months Ended
	Jul. 31, 2011	May 31, 2011 Common Class A [Member]	Jul. 31, 2011 Common Class A [Member]	Jan. 31, 2011 Common Class A [Member]	Jul. 31, 2011 Common Class B [Member]	Jan. 31, 2011 Common Class B [Member]	Sep. 14, 2011 Series A Preferred Stock [Member]	Jul. 31, 2011 Series A Preferred Stock [Member]	Jul. 31, 2010 Series A Preferred Stock [Member]	Jul. 31, 2011 Series A Preferred Stock [Member]	Jul. 31, 2010 Series A Preferred Stock [Member]	Jan. 31, 2011 Series A Preferred Stock [Member]	Mar. 09, 2010 Series A Preferred Stock [Member]	Mar. 04, 2010 Series A Preferred Stock [Member]	Mar. 04, 2010 Senior notes due 2011 [Member]	Mar. 04, 2010 Senior notes due 2015 [Member]	Mar. 04, 2010 Senior notes due 2017 [Member]	May 31, 2011 5.000% Convertible Senior Notes due 2016 [Member]	Jan. 31, 2011 5.000% Convertible Senior Notes due 2016 [Member]
Class of Stock [Line Items]
Common stock voting right percentage			25.00%		75.00%
Common stock voting right			One vote per share		Ten vote per share
Number of authorized shares of common stock			371,000,000	371,000,000	56,000,000	56,000,000
Repayment of debt by issuing Class A common stock	$ 48,742,000		$ 1,148,000															$ 40,000,000	$ 110,000,000
Share of Class A common stock		3,444,293	3,444,000
Common stock, shares issued			148,269,583	144,251,634	20,987,364	21,218,753
Preferred stock, shares authorized								6,400,000		6,400,000		6,400,000		6,400,000
Senior note exchanged for preferred stock series A, value of senior note exchanged															51,176,000	121,747,000	5,826,000
Value of preferred stock exchanged for senior notes															50,664,000	114,442,000	4,894,000
Series A preferred stock issued														50,000,000
Proceeds from series A preferred stock issuance										26,900,000
Stock conversion description	Holder would receive approximately 3.3 shares of Class A common stock per $50 liquidation preference of Series A preferred stock
Initial conversion price of class A common stock			$ 15.12
Preferred stock conversion description										Daily Volume Weighted Average Price of our Class A common stock equals or exceeds 150% of the initial conversion price then in effect for at least 20 out of 30 consecutive trading days
Undeclared Series A preferred stock dividends										1,925,000
Declared paid and unpaid cash dividends on preferred stock series A							$ 3,850,000	$ 3,850,000	$ 4,107,000	$ 7,700,000	$ 4,107,000
Series A preferred stock issued								4,399,998		4,399,998		4,399,998	4,400,000
Capital Stock (Textuals)
Equity call hedge transaction conversion price	$ 18.27
Preferred stock, shares authorized								6,400,000		6,400,000		6,400,000		6,400,000