Stockholders' Equity - Schedule of Common Stock Reserved for Future Issuance (Parenthetical) (Details) - shares	Jan. 01, 2019	Mar. 31, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Treasury stock, shares at cost		371,664	357,314
2016 Equity Incentive Plan
Class Of Stock [Line Items]
Number of authorized shares increased	384,045