Derivative Instruments, Hedging Activities and Accumulated Other Comprehensive Income (Details) (USD $)			9 Months Ended														3 Months Ended		9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Gains and (Losses) on Cash Flow Hedges [Member]	Sep. 30, 2013 Interest Rate Swap [Member]	Sep. 30, 2012 Interest Rate Swap [Member]	Aug. 31, 2010 Interest Rate Swap [Member]	Sep. 30, 2013 Designated as Hedging Instrument [Member] Interest Rate Swap [Member]	Dec. 31, 2012 Designated as Hedging Instrument [Member] Interest Rate Swap [Member]	Sep. 30, 2013 Designated as Hedging Instrument [Member] Accrued liabilities and other [Member] Interest Rate Swap [Member]	Dec. 31, 2012 Designated as Hedging Instrument [Member] Accrued liabilities and other [Member] Interest Rate Swap [Member]	Sep. 30, 2013 Designated as Hedging Instrument [Member] Deferred charges, and other assets net [Member] Interest Rate Swap [Member]	Dec. 31, 2012 Designated as Hedging Instrument [Member] Deferred charges, and other assets net [Member] Interest Rate Swap [Member]	Sep. 30, 2013 Not Designated as Hedging Instrument [Member] Interest Rate Swap [Member]	Dec. 31, 2012 Not Designated as Hedging Instrument [Member] Interest Rate Swap [Member]	Sep. 30, 2013 Not Designated as Hedging Instrument [Member] Accrued liabilities and other [Member] Interest Rate Swap [Member]	Dec. 31, 2012 Not Designated as Hedging Instrument [Member] Accrued liabilities and other [Member] Interest Rate Swap [Member]	Sep. 30, 2013 Interest Expense [Member]	Sep. 30, 2012 Interest Expense [Member]	Sep. 30, 2013 Interest Expense [Member]	Sep. 30, 2012 Interest Expense [Member]
Derivative Instruments, Hedging Activities and Accumulated Other Comprehensive Income [Abstract]
Notional amount of cash flow hedges	$ 174,600,000
Derivative Instruments, Gain (Loss) [Line Items]
Changes in fair value recorded in interest expense																	(33,000)	(55,000)	(239,000)	(106,000)
Amount reclassified as an increase to interest expense during next twelve months																			1,600,000
Derivatives, Fair Value [Line Items]
Amount of notional principal interest rate swap					174,600,000	63,300,000
Derivative, expiry date				Jul. 31, 2013
Derivatives Liabilities, Fair Value									1,598,000	1,613,000					0	239,000
Derivative Assets, Fair Value											(5,019,000)	(177,000)
Derivative Assets (Liabilities), at Fair Value, Net							(3,421,000)	1,436,000					0	239,000
Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), before Tax			(1,436,000)
Other Comprehensive Income Loss Before Reclassifications Before Tax			3,623,000
Amounts reclassified from accumulated other comprehensive income (to interest expense), before tax			1,234,000
Net current period other comprehensive income before tax			4,857,000
Accumulated Other Comprehensive Income (Loss), before Tax			3,421,000
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Tax			573,000
Other comprehensive income before reclassifications, tax			(1,452,000)
Amounts reclassified From accumulated other comprehensive income tax (to interest expense)			(496,000)
Net current period other comprehensive income, tax			(1,948,000)
Accumulated Other Comprehensive Income (Loss), Tax			(1,375,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total	2,046,000	(863,000)	(863,000)
Other comprehensive income before reclassifications, net of tax			2,171,000
Amounts reclassified from accumulated other comprehensive income (to interest expense), net of tax			738,000
Net current period other comprehensive income, net of tax			2,909,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total	$ 2,046,000	$ (863,000)	$ 2,046,000