Derivative Instruments and Hedging Activities (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Aug. 31, 2010
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total	$ 1,122,000	$ 2,594,000
Gains and (Losses) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), before Tax	4,336,000
Other comprehensive income (loss) before reclassifications, before Tax	(4,186,000)
Amounts reclassified from accumulated other comprehensive income (to interest expense), before tax	1,721,000
Net current period other comprehensive income (loss), before tax	(2,465,000)
Accumulated Other Comprehensive Income (Loss), before Tax	1,871,000
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Tax	(1,742,000)
Other comprehensive income (loss) before reclassifications, tax	1,676,000
Amounts reclassified From accumulated other comprehensive income tax (to interest expense)	(683,000)
Net current period other comprehensive income (loss), tax	993,000
Accumulated Other Comprehensive Income (Loss), Tax	(749,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total	2,594,000
Other comprehensive income (loss) before reclassifications, net of tax	(2,510,000)
Amounts reclassified from accumulated other comprehensive income (to interest expense), net of tax	1,038,000
Net current period other comprehensive income (loss), net of tax	(1,472,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total	1,122,000
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Changes in fair value recorded in interest expense		239,000	213,000
Amount reclassified as an increase to interest expense during next twelve months	1,300,000
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative, expiry date	Jul. 31, 2013
Amount of notional principal interest rate swap				174,600,000	63,300,000
Notional amount of interest rate swaps	170,300,000	174,600,000
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	1,871,000	4,336,000
Designated as Hedging Instrument [Member] | Accrued liabilities and other [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Derivatives Liabilities, Fair Value	(1,309,000)	(1,590,000)
Designated as Hedging Instrument [Member] | Deferred charges and other assets, net [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Fair Value	3,180,000	5,926,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Notional amount of interest rate swaps			$ 52,200,000