Derivative Instruments (Classification of Changes in Fair Value) (Details) (Interest Rate Swap, USD $) In Thousands, unless otherwise specified			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 29, 2011	Jun. 30, 2012 Designated as Hedging Instrument Interest Expense Cash Flow Hedging	Jun. 30, 2011 Designated as Hedging Instrument Interest Expense Cash Flow Hedging	Jun. 30, 2012 Designated as Hedging Instrument Interest Expense Cash Flow Hedging	Jun. 30, 2011 Designated as Hedging Instrument Interest Expense Cash Flow Hedging	Jun. 30, 2012 Not Designated as Hedging Instrument Fair Value Adjustments on Hedges and Derivative Contracts Cash Flow Hedging	Jun. 30, 2011 Not Designated as Hedging Instrument Fair Value Adjustments on Hedges and Derivative Contracts Cash Flow Hedging	Jun. 30, 2012 Not Designated as Hedging Instrument Fair Value Adjustments on Hedges and Derivative Contracts Cash Flow Hedging	Jun. 30, 2011 Not Designated as Hedging Instrument Fair Value Adjustments on Hedges and Derivative Contracts Cash Flow Hedging
Derivative [Line Items]
Aggregate notional amount of derivatives	$ 0	$ 500,000
Gain recognized in OCI on derivative (effective portion)				0		0
Gain (loss) reclassified from AOCI into income (ineffective portion)			$ 0	$ (6,063)	$ 0	$ (11,824)	$ 0	$ 48	$ 0	$ 265