Summary of Significant Accounting Policies (Details 2) (USD $)	3 Months Ended		6 Months Ended									6 Months Ended	12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Robert A. Alter	Dec. 31, 2011 Robert A. Alter item	Jun. 30, 2014 Total at the end of the period	Dec. 31, 2013 Total at the end of the period	Jun. 30, 2014 Level 2	Dec. 31, 2013 Level 2	Jun. 30, 2014 Level 3	Dec. 31, 2013 Level 3	Jun. 30, 2014 Interest Rate Cap Agreement item	Dec. 31, 2013 Interest Rate Cap Agreement item	Jun. 30, 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
Impairment loss on continuing operations	$ 0	$ 0	$ 0	$ 0
Goodwill impairment loss	0	0	0	0
Percentage of debt having fixed interest rates	70.70%		70.70%		70.70%
Carrying value of secured debt	1,392,422,000		1,392,422,000		1,404,075,000
Weighted average cost of debt (as a percent)												5.00%	5.00%
Fair value of debt												1,400,000,000	1,400,000,000
Assets:
Interest rate cap derivative agreements	2,000		2,000		16,000			2,000	16,000	2,000	16,000
Life insurance policy								1,214,000	1,385,000	1,214,000	1,385,000
Total assets								1,216,000	1,401,000	1,216,000	1,401,000
Liabilities:
Interest rate swap derivative agreements								818,000	1,066,000	818,000	1,066,000
Retirement benefit agreement								1,214,000	1,385,000	1,214,000	1,385,000
Total liabilities								2,032,000	2,451,000	2,032,000	2,451,000
Accounts Receivable
Allowance for doubtful accounts (in dollars)	200,000		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