Net Income Per Share (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2012 Stock Options [Member]	Jun. 30, 2012 Stock Options [Member]	Sep. 30, 2011 Convertible Debt Securities [Member]	Jun. 30, 2012 Convertible Debt Securities [Member]	Sep. 30, 2011 Convertible Debt Securities [Member]	Sep. 30, 2012 Stock Options [Member]
Earnings Per Share, Basic & Dilutive, by Common Class, Including Two Class Method [Line Items]
NET INCOME	$ 235,669,000	$ 26,206,000	$ 256,272,000	$ 66,701,000
Weighted Average Number of Shares Outstanding, Basic	42,024,000	45,463,000	43,761,000	45,380,000
Weighted Average Number Diluted Shares Outstanding Adjustment	329,000	818,000	311,000	620,000
Weighted Average Number of Shares Outstanding, Diluted	42,353,000	46,281,000	44,072,000	46,000,000
Net Incme Per Common Share, Basic	$ 5.61	$ 0.58	$ 5.86	$ 1.47
Dilutive Securities, Effect on Basic Earnings Per Share	$ (0.05)	$ (0.01)	$ (0.05)	$ (0.02)
Net Income Per Common Share, Diluted	$ 5.56	$ 0.57	$ 5.81	$ 1.45
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount					0	0	3,700,000	4,000,000	3,900,000	0
Class of Warrant or Right, Outstanding	4,000,000		4,000,000