Summary of Significant Accounting Policies (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Property and equipment
Accumulated depreciation	$ 127,664,000		$ 127,664,000		$ 124,181,000
Point loyalty program
Point loyalty program	1,760,000		1,760,000		$ 1,777,000
Revenue and expense recognition
Goods and services provided without charge to customers as promotional items	4,083,000	$ 4,603,000	8,294,000	$ 9,073,000
Advertising costs
Advertising expenses	$ 536,000	$ 494,000	$ 1,062,000	$ 1,042,000