Benefit Plans - 401(k) Savings Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
401(k) Savings Plan
Maximum discretionary contribution matched by employer for each employee's contribution	$ 1,500	$ 1,000	$ 1,000
Contribution expense	$ 342,000	$ 206,000	$ 196,000