Schedule II Financial Information of Registrant Parent Company Balance Sheet (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Condensed Financial Statements, Captions [Line Items]
Trading Securities	$ 4,094,622,000	$ 4,211,059,000
Short-term Investments	777,532,000	1,261,703,000
Cash and Cash Equivalents, at Carrying Value	31,555,000	35,589,000	20,334,000	41,574,000
Restricted cash	24,226,000	27,020,000
Restricted Net Assets Held by Consolidated Subsidiaries	1,200,000,000
Property, Plant and Equipment, Net	7,456,000	11,044,000
Other Assets	374,662,000	333,566,000
Assets	5,903,200,000	6,656,765,000	7,620,887,000
Long-term debt	663,571,000	818,584,000
Liabilities	5,166,875,000	5,474,474,000
Common Stock, Value, Issued	151,000	151,000
Treasury Stock, Value	(892,094,000)	(892,052,000)
Additional paid-in capital	1,967,414,000	1,966,565,000
Retained earnings (deficit)	(355,241,000)	96,227,000
Accumulated other comprehensive income (loss)	16,095,000	11,400,000
Total stockholders’ equity	736,325,000	1,182,291,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	98,909,000	96,403,000
Common Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Common Stock, Shares Authorized	325,000,000	325,000,000
Common Stock, Shares, Issued	151,131,173	150,666,446
Common Stock, Shares, Outstanding	133,647,216	133,199,159
Treasury Stock, Shares	17,483,957	17,467,287
Parent Company
Condensed Financial Statements, Captions [Line Items]
Trading Securities	99,171,000	387,239,000
Short-term Investments	136,075,000	177,116,000
Other Investments and Securities, at Cost	16,666,000	25,000,000
Cash and Cash Equivalents, at Carrying Value	2,978,000	453,000	1,945,000	325,000
Restricted cash	360,000	1,060,000
Restricted Net Assets Held by Consolidated Subsidiaries	1,234,229,000	1,591,914,000
Unamortized Debt Issuance Expense	8,582,000	8,414,000
Related Party Transaction, Due from (to) Related Party	17,690,000	2,451,000
Property, Plant and Equipment, Net	1,344,000	2,017,000
Other Assets	33,524,000	35,474,000
Assets	1,550,619,000	2,231,138,000
Accounts Payable and Other Accrued Liabilities	54,869,000	123,665,000
Interest Payable	3,959,000	7,558,000
Long-term debt	663,571,000	818,584,000
Accrued Income Taxes	91,895,000	99,040,000
Liabilities	814,294,000	1,048,847,000
Common Stock, Value, Issued	151,000	151,000
Treasury Stock, Value	(892,094,000)	(892,052,000)
Additional paid-in capital	1,967,414,000	1,966,565,000
Retained earnings (deficit)	(355,241,000)	96,227,000
Accumulated other comprehensive income (loss)	16,095,000	11,400,000
Total stockholders’ equity	736,325,000	1,182,291,000
Total Liabilities And Stockholders Equity Parent Company	1,550,619,000	2,231,138,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ 48,786,000	$ 46,998,000
Common Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Common Stock, Shares Authorized	325,000,000	325,000,000
Common Stock, Shares, Issued	151,131,173	150,666,446
Common Stock, Shares, Outstanding	133,647,216	133,199,159
Treasury Stock, Shares	17,483,957	17,467,287