Income Taxes - Schedule of Difference of Income Tax Expense from the United States Federal Income Tax Rates (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amount
Tax expense at statutory rate	$ 11,415,000	$ 13,683,000	$ 18,370,000
State taxes, net	1,626,000	1,278,000	1,590,000
Permanent differences	2,060,000	221,000	278,000
Change in statutory rate	(3,741,000)	0	0
Other	133,000	(242,000)	(166,000)
Income Tax Expense	$ 11,493,000	$ 14,940,000	$ 20,072,000
Percentage
Tax expense at statutory rate (as a percent)	35.00%	35.00%	35.00%
State taxes, net (as a percent)	4.98%	3.27%	3.03%
Permanent differences (as a percent)	6.31%	0.56%	0.53%
Change in statutory rate (as a percent)	(11.47%)	0.00%	0.00%
Other (as a percent)	0.42%	(0.62%)	(0.32%)
Total percentage	35.24%	38.21%	38.24%