Derivatives (Textual) (Details) (USD $)	6 Months Ended		3 Months Ended	6 Months Ended					3 Months Ended		3 Months Ended		3 Months Ended				3 Months Ended
	Jun. 30, 2013 Interest Rate Cash Flow Hedges [Member]	Jun. 30, 2012 Interest Rate Cash Flow Hedges [Member]	Mar. 31, 2010 Interest rate cap [Member] Interest Rate Cash Flow Hedges [Member] agreement	Jun. 30, 2013 Interest rate cap [Member] Interest Rate Cash Flow Hedges [Member]	Jun. 30, 2013 Interest rate swap [Member]	Mar. 31, 2013 Interest rate swap [Member]	Dec. 31, 2012 Interest rate swap [Member]	Jun. 30, 2011 USR Swap one [Member] agreement	Jun. 30, 2011 USR Swap one [Member] Interest Rate Cash Flow Hedges [Member]	Jun. 30, 2013 USR Swap one [Member] Interest Rate Cash Flow Hedges [Member]	Jun. 30, 2011 USR Swap two [Member] Interest Rate Cash Flow Hedges [Member]	Jun. 30, 2013 USR Swap two [Member] Interest Rate Cash Flow Hedges [Member]	Mar. 31, 2010 LIBOR [Member] Interest rate cap [Member]	Mar. 31, 2013 LIBOR [Member] Interest rate swap [Member]	Dec. 31, 2012 LIBOR [Member] Interest rate swap [Member]	Jun. 30, 2013 LIBOR [Member] Interest rate swap [Member]	Jun. 30, 2011 LIBOR [Member] USR Swap one [Member] Interest Rate Cash Flow Hedges [Member]	Jun. 30, 2011 LIBOR [Member] USR Swap two [Member] Interest Rate Cash Flow Hedges [Member]
Derivative [Line Items]
Variable bank rate debt	$ 162,300,000	$ 155,421,000
Variable rate debt as a percent of total debt (percent)	29.90%	24.40%
Expected reclassification from accumulated other comprehensive loss to interest expense and other, net	700,000
Number of agreements			3					2
Derivative variable rate basis													LIBOR	one-month LIBOR	one-month LIBOR		one-month LIBOR	one-month LIBOR
Maturity				Feb. 01, 2014					Oct. 01, 2015		Apr. 01, 2014
Notional amount			150,000,000		4,249,000		4,718,000			2,440,000		880,000
LIBOR on cap purchase (percent)			4.50%
Paid for cap purchase amortized as interest expense			$ 1,537,000
Fixed rate of interest paid by the Company (percent)						2.873%	3.75%		5.71%		4.15%
Recorded interest expense rate (percent)						2.873%	3.75%		8.71%		6.15%
Underlying debt interest rate (percent)									3.00%		2.00%
Interest rate agreement, basis spread on variable rate (percent)						2.00%	2.50%								2.50%	2.00%