Long-Term Debt and Loan Agreements - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	May. 30, 2014	Dec. 13, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Letters of credit	$ 4,300,000
Long-term debt, excluding unamortized deferred financing costs	218,471,000		$ 191,881,000
Less unamortized deferred financing fees	1,514,000		$ 1,631,000
Loan Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity on line of credit				$ 300,000,000	$ 200,000,000	$ 180,000,000
Remaining amount available under the line of credit	$ 175,700,000
Interest rate during period	4.50%	4.54%