Employee Benefit Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Benefit Plans [Abstract]
Percentage of annual compensation per employee	6.00%
Defined contribution plan contributions by employer	$ 3,000
Defined contribution plan employers matching contribution annual vesting percentage after three years	100.00%
Period of defined contribution plan employers matching contribution annual vesting 100 percentage	3 years
Defined contribution plan employers matching contribution annual vesting percentage	20.00%
Defined contribution plan employers matching contribution annual vesting period	2 years
Defined contribution plan, employer contributions	$ 800,000	$ 800,000	$ 800,000