CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (USD $) In Thousands, unless otherwise specified	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income	Common Stock in Treasury	Noncontrolling Interest	Total
Balance at Dec. 31, 2008	$ 3,436	$ 811,492	$ 1,449,977	$ 247,665	$ (4,740)	$ 10,133	$ 2,517,963
Balance, shares at Dec. 31, 2008	343,625
Comprehensive income (loss):
Net income (loss)	0	0	(35,650)	0	0	(142)	(35,792)
Other comprehensive income (loss)	0	0	0	(163,389)	0		(163,389)
Total comprehensive income (loss)						(142)	(199,181)
Stock-based compensation	0	16,003	0	0	0		16,003
Exercise of stock options, shares	2,153
Exercise of stock options	22	5,733	0	0	0		5,755
Issuance of restricted stock, shares	312
Issuance of restricted stock	3	(3)	0	0	0		0
Cancellation of restricted stock, shares	(10)
Cancellation of restricted stock	0	0	0	0	0		0
Issuance of stock awards, shares	1
Issuance of stock awards	0	65	0	0	0		65
Treasury stock - non-qualified plan	0	204	0	0	407		611
Distributions to noncontrolling interest in partnership	0	0	0	0	0	(235)	(235)
Balance at Dec. 31, 2009	3,461	833,494	1,414,327	84,276	(4,333)	9,756	2,340,981
Balance, shares at Dec. 31, 2009	346,081
Comprehensive income (loss):
Net income (loss)	0	0	604,118	0	0	(285)	603,833
Other comprehensive income (loss)	0	0	0	(301)	0	0	(301)
Total comprehensive income (loss)						(285)	603,532
Stock-based compensation	0	16,569	0	0	0	0	16,569
Exercise of stock options, shares	1,293
Exercise of stock options	12	3,885	0	0	0	0	3,897
Issuance of restricted stock, shares	392
Issuance of restricted stock	4	(4)	0	0	0	0	0
Cancellation of restricted stock, shares	(30)
Cancellation of restricted stock	0	0	0	0	0	0	0
Tax withholding - stock compensation, shares	(3)
Tax withholding - stock compensation	0	(112)	0	0	0	0	(112)
Issuance of stock awards, shares	1
Issuance of stock awards	0	37	0	0	0	0	37
Treasury stock - non-qualified plan	0	771	0	0	889	0	1,660
Distributions to noncontrolling interest in partnership	0	0	0	0	0	(188)	(188)
Purchase of noncontrolling interest in partnership	0	7,783	0	0	0	(9,283)	(1,500)
Balance at Dec. 31, 2010	3,477	862,423	2,018,445	83,975	(3,444)	0	2,964,876
Balance, shares at Dec. 31, 2010	347,734
Comprehensive income (loss):
Net income (loss)	0	0	637,769	0	0	0	637,769
Other comprehensive income (loss)	0	0	0	324,453	0	0	324,453
Total comprehensive income (loss)						0	962,222
Tax benefit for stock-based compensation	0	14,626	0	0	0	0	14,626
Stock-based compensation	0	19,036	0	0	0	0	19,036
Exercise of stock options, shares	851
Exercise of stock options	9	6,403	0	0	0	0	6,412
Issuance of restricted stock, shares	532
Issuance of restricted stock	5	(5)	0	0	0	0	0
Cancellation of restricted stock, shares	(52)
Cancellation of restricted stock	0	1	0	0	0	0	1
Tax withholding - stock compensation, shares	(7)
Tax withholding - stock compensation		(262)	0	0	0	0	(262)
Issuance of stock awards, shares	1
Issuance of stock awards	0	42	0	0	0	0	42
Treasury stock - non-qualified plan	0	1,135	0	0	1,216	0	2,351
Balance at Dec. 31, 2011	$ 3,491	$ 903,399	$ 2,656,214	$ 408,428	$ (2,228)	$ 0	$ 3,969,304
Balance, shares at Dec. 31, 2011	349,059