Unaudited Condensed Consolidated Statements of Shareholders' Equity (USD $) In Thousands	Total	[CommonStockMember]	[PreferredStockMember]	[AdditionalPaidInCapitalMember]	[AccumulatedOtherComprehensiveIncomeMember]	[RetainedEarningsMember]	[TreasuryStockMember]
Balance at beginning of period at Dec. 31, 2010		$ 84,033	$ 20,800	$ 3,419,864	$ 4,056	$ 4,761,178	$ (1,083,012)
Net income (loss)	(502,648)					(502,648)
Dividends on common shares						(118,392)
Dividends on preferred shares	(31,614)					(31,614)
Issuance of common shares		548		29,774
Issuance of preferred shares			14,950	346,772
Change in currency translation adjustment	(10,874)				(10,874)
Change in other accumulated comprehensive loss	(1,049)				(1,049)
Repurchase of common shares							(226,703)
Balance at end of period at Sep. 30, 2011	6,707,683	84,581	35,750	3,796,410	(7,867)	4,108,524	(1,309,715)
Balance at beginning of period at Dec. 31, 2011	6,467,542	84,767	35,750	3,803,796	(12,644)	4,035,103	(1,479,230)
Net income (loss)	1,022,994					1,022,994
Dividends on common shares						(118,152)
Dividends on preferred shares	(46,216)					(46,216)
Issuance of common shares		437		36,845
Issuance of preferred shares			0	0
Change in currency translation adjustment	31,042				31,042
Change in other accumulated comprehensive loss	(883)				(883)
Repurchase of common shares							(314,607)
Balance at end of period at Sep. 30, 2012	$ 7,079,002	$ 85,204	$ 35,750	$ 3,840,641	$ 17,515	$ 4,893,729	$ (1,793,837)