Summary of Significant Accounting Policies (Reconciliation of Net Income to Taxable Income Before Dividends Paid Deduction) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounting Policies [Abstract]
Net income (loss)	$ (75,868)	$ 96,309	$ 65,262
Book/tax differences	148,456	(12,885)	74,065
Taxable income before adjustments	72,588	83,424	139,327
Less: capital gains	0	0	(62,403)
Adjusted taxable income subject to 90% distribution requirement	$ 72,588	$ 83,424	$ 76,924