Summary of Significant Accounting Policies (Details 2) (USD $)									3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2013 Robert A. Alter	Dec. 31, 2011 Robert A. Alter item	Mar. 31, 2014 Total at the end of the period	Dec. 31, 2013 Total at the end of the period	Mar. 31, 2014 Level 2	Dec. 31, 2013 Level 2	Mar. 31, 2014 Level 3	Dec. 31, 2013 Level 3	Mar. 31, 2014 Interest Rate Cap Agreement item	Dec. 31, 2013 Interest Rate Cap Agreement item	Mar. 31, 2014 Interest Rate Swap Agreement item	Dec. 31, 2013 Interest Rate Swap Agreement item
Fair value of assets and liabilities measured at fair value on a recurring and non-recurring basis
Number of derivative agreements											2	2
Number of derivative agreements													1	1
Percentage of debt having fixed interest rates	70.70%	70.70%
Carrying value of secured debt	$ 1,398,402,000	$ 1,404,075,000
Weighted average cost of debt (as a percent)									5.00%
Fair value of debt									1,400,000,000	1,400,000,000
Assets:
Interest rate cap derivative agreements	10,000	16,000			10,000	16,000	10,000	16,000
Life insurance policy					1,203,000	1,385,000	1,203,000	1,385,000
Total assets					1,213,000	1,401,000	1,213,000	1,401,000
Liabilities:
Interest rate swap derivative agreements					952,000	1,066,000	952,000	1,066,000
Retirement benefit agreement					1,203,000	1,385,000	1,203,000	1,385,000
Total liabilities					2,155,000	2,451,000	2,155,000	2,451,000
Accounts Receivable
Allowance for doubtful accounts (in dollars)	200,000	200,000
Number of installments to be paid out under the Retirement Benefit Agreement				10
Amount paid under the Retirement Benefit Agreement			$ 800,000