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)	(682,771)					(682,771)
Dividends on common shares						(77,746)
Dividends on preferred shares	(17,263)					(17,263)
Issuance of common shares		536		25,421
Issuance of preferred shares			14,950	346,772
Change in currency translation adjustment	44,084				44,084
Change in other accumulated comprehensive loss	(2,155)				(2,155)
Repurchase of common shares							(226,703)
Balance at end of period at Jun. 30, 2011	6,632,044	84,569	35,750	3,792,057	45,985	3,983,398	(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)	536,287					536,287
Dividends on common shares						(79,924)
Dividends on preferred shares	(30,811)					(30,811)
Issuance of common shares		375		28,125
Issuance of preferred shares			0	0
Change in currency translation adjustment	(1,950)				(1,950)
Change in other accumulated comprehensive loss	(56)				(56)
Repurchase of common shares							(221,995)
Balance at end of period at Jun. 30, 2012	$ 6,697,593	$ 85,142	$ 35,750	$ 3,831,921	$ (14,650)	$ 4,460,655	$ (1,701,225)