Debt Obligations (Outstanding Unsecured Notes in Series of Transactions) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Schedule of principal payments of debt obligations
Repurchase Amount	$ 188,430
Principal	164,968
Loss	21,939
Deferred Financing Amortization	451
2012 5.750% Notes [Member]
Schedule of principal payments of debt obligations
Repurchase Amount	309
Principal	301
Loss	2
Deferred Financing Amortization	0
Debt instrument stated interest rate	5.75%
2014 5.400% Notes
Schedule of principal payments of debt obligations
Repurchase Amount	4,630
Principal	4,302
Loss	264
Deferred Financing Amortization	8
Debt instrument stated interest rate	5.40%
2015 7.500% Notes [Member]
Schedule of principal payments of debt obligations
Repurchase Amount	69,549
Principal	60,794
Loss	8,712
Deferred Financing Amortization	183
Debt instrument stated interest rate	7.50%
Senior Notes Due2016 [Member] [Member]
Schedule of principal payments of debt obligations
Repurchase Amount	113,942
Principal	99,571
Loss	12,961
Deferred Financing Amortization	$ 260