Company Inquiry and Restatement (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2012		Dec. 31, 2011		Mar. 31, 2013		Dec. 31, 2012
Stockholders' Equity Attributable To Parent	$ 976,944		$ 1,555,245		$ 372,860		$ 534,246
Cumulative adjustment to retained earnings as of December 31, 2011	(552,953)	[1]
Stockholders Equity As Restated	1,002,292
Retained Earnings [Member]
Stockholders' Equity Attributable To Parent	1,467,734		2,040,031		856,718		1,024,480
Cumulative adjustment to retained earnings as of December 31, 2011	(535,437)	[1]
Stockholders Equity As Restated	1,504,594		1,504,594
Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders' Equity Attributable To Parent	(109,737)	[2]	(101,791)	[2]	(105,581)	[2]	(113,781)	[2]
Cumulative adjustment to retained earnings as of December 31, 2011	(17,516)	[1],[2]
Stockholders Equity As Restated	(119,307)	[2]	(119,307)
Scenario, Previously Reported [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			2,040,031
Scenario, Previously Reported [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders' Equity Attributable To Parent			(101,791)
Tax Adjustment On 2000 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			(122,500)
Tax Adjustment On 2001 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			(36,364)
Tax Adjustment On 2002 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			12,919
Tax Adjustment On 2003 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			(23,405)
Tax Adjustment On 2004 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			(7,317)
Tax Adjustment On 2005 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			(18,342)
Tax Adjustment On 2006 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			(337,404)
Tax Adjustment On 2007 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			(46,193)
Tax Adjustment On 2008 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			43,130
Tax Adjustment On 2009 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			(3,215)
Tax Adjustment On 2010 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			11,701
Tax Adjustment On 2011 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			(6,948)
Cumulative adjustment to retained earnings as of December 31, 2011			(535,437)
Tax Adjustment On 2011 [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Cumulative adjustment to retained earnings as of December 31, 2011			(17,516)
Credit Valuation Adjustment On 2011 [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable To Parent			(1,499)
Credit Valuation Adjustment On 2011 [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders' Equity Attributable To Parent			$ (17,516)

[1] See Note 2, "Company Inquiry and Restatement," to the accompanying condensed consolidated financial statements for details.

[2] Amounts are net of tax.