Debt Schedule of Long-Term Debt Repayments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Debt Instrument [Line Items]
Repayments of Long-term Debt			$ 101,252	$ 804,304
Secured Debt [Member] | 2011 Senior Secured Credit Facility [Member]
Debt Instrument [Line Items]
Repayments of Long-term Debt	3,750	3,750	11,252	3,750
Secured Debt [Member] | 2007 Senior Secured Credit Facility [Member]
Debt Instrument [Line Items]
Repayments of Long-term Debt	0	351,320	0	406,950
Secured Debt [Member] | Credit Facilities [Member]
Debt Instrument [Line Items]
Repayments of Long-term Debt	33,750	525,070	101,252	580,700
Line of Credit [Member] | Secured Debt [Member] | 2011 Senior Secured Credit Facility [Member]
Debt Instrument [Line Items]
Repayments of Long-term Debt	30,000	0	90,000	0
Line of Credit [Member] | Secured Debt [Member] | 2007 Senior Secured Credit Facility [Member]
Debt Instrument [Line Items]
Repayments of Long-term Debt	$ 0	$ 170,000	$ 0	$ 170,000