Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Earnings Per Share [Abstract]
Net earnings	$ 90,726		$ 75,773		$ 240,569		$ 182,091
Weighted average shares outstanding:
Basic (in shares)	72,546		70,994		72,017		70,784
Dilutive potential common shares from stock options and restricted stock	1,679	[1]	701	[1]	1,508	[1]	863	[1]
Dilutive potential common shares from conversion of Convertible Notes and Warrants	4,186	[2]	0	[2]	1,364	[2]	0	[2]
Diluted (in shares)	78,411		71,695		74,889		71,647
Basic net earnings per share (in dollars per share)	$ 1.25		$ 1.07		$ 3.34		$ 2.57
Diluted net earnings per share (in dollars per share)	$ 1.16		$ 1.06		$ 3.21		$ 2.54
Antidilutive stock options and restricted stock excluded from computation of earnings per share (in shares)	43		3,931		1,109		4,156
Average price of common stock	$ 66.18		$ 35.10		$ 57.15		$ 40.33
Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Conversion price (in dollars per share)	$ 51.34		$ 51.34		$ 51.34		$ 51.34
Exercise price of warrants (in dollars per share)	60.41		60.41		60.41		60.41

[1] Potentially dilutive stock options and restricted stock totaling 43 shares and 3,931 shares for the three months ended September 30, 2011 and 2010, respectively, and 1,109 shares and 4,156 shares for the nine months ended September 30, 2011 and 2010, respectively, were excluded from the computation of diluted weighted average shares outstanding due to their antidilutive effect.

[2] The average price of our common stock was $66.18 and $35.10 for the three months ended September 30, 2011 and 2010, respectively, and $57.15 and $40.33 for the nine months ended September 30, 2011 and 2010, respectively.