Derivative Financial Instruments Activity of Hedging Instruments in Accumulated OCI (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Accumulated Net Gain (Loss) from Derivative and Nonderivative Instruments Designated as Hedging Instruments [Member]	Dec. 31, 2012 Accumulated Net Gain (Loss) from Derivative and Nonderivative Instruments Designated as Hedging Instruments [Member]	Sep. 30, 2012 Accumulated Net Gain (Loss) from Derivative and Nonderivative Instruments Designated as Hedging Instruments [Member]	Dec. 31, 2011 Accumulated Net Gain (Loss) from Derivative and Nonderivative Instruments Designated as Hedging Instruments [Member]	Sep. 30, 2013 Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	Dec. 31, 2012 Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	Sep. 30, 2012 Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	Dec. 31, 2011 Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period			$ (34,384)		$ (15,805)	$ (16,069)	$ (16,057)	$ (14,380)	$ (1,425)	$ (1,689)	$ (1,677)	$ 0
Unrealized gain (loss) on derivative instruments	(678)	(828)	94	(1,677)
Realized losses reclassified into net income (loss)	170	0	170	0
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	$ (36,333)		$ (36,333)		$ (15,805)	$ (16,069)	$ (16,057)	$ (14,380)	$ (1,425)	$ (1,689)	$ (1,677)	$ 0