401(k) savings plan	12 Months Ended
Dec. 31, 2019
Retirement Benefits [Abstract]
401(k) savings plan	401(k) Savings planIn 1997, the Company established a defined-contribution savings plan under Section 401(k) of the Internal Revenue Code (“the 401(k) Plan”). The 401(k) Plan covers all employees who meet defined minimum age and service requirements, and allows participants to defer a portion of their annual compensation on a pretax basis. In March 2020, the Company expects to make matching contributions of approximately $4.6 million related to employee contributions made during 2019. In February 2019, the Company made $2.4 million of matching contributions related to employee contributions made during 2018. The match contribution is included in accrued expenses and other current liabilities as of December 31, 2019 and 2018. Expense related to the 401(k) Plan totaled $4.6 million, $2.4 million, $1.5 million for the years ended December 31, 2019, 2018, and 2017, respectively.

401(k) savings plan

12 Months Ended

Dec. 31, 2019

401(k) Savings planIn 1997, the Company established a defined-contribution savings plan under Section 401(k) of the Internal Revenue Code (“the 401(k) Plan”). The 401(k) Plan covers all employees who meet defined minimum age and service requirements, and allows participants to defer a portion of their annual compensation on a pretax basis. In March 2020, the Company expects to make matching contributions of approximately $4.6 million related to employee contributions made during 2019. In February 2019, the Company made $2.4 million of matching contributions related to employee contributions made during 2018. The match contribution is included in accrued expenses and other current liabilities as of December 31, 2019 and 2018. Expense related to the 401(k) Plan totaled $4.6 million, $2.4 million, $1.5 million for the years ended December 31, 2019, 2018, and 2017, respectively.