Quarterly report pursuant to Section 13 or 15(d)

Common Stock - Summary of Restricted Stock Unit Award Activity (Detail)

v3.19.1
Common Stock - Summary of Restricted Stock Unit Award Activity (Detail) - Restricted Stock Unit [Member]
3 Months Ended
Mar. 31, 2019
$ / shares
shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]  
Number of Shares, Beginning Balance | shares 15,142
Number of Shares, Released | shares (133)
Number of Shares, Ending Balance | shares 15,009
Weighted-Average Grant Date Fair Value, Beginning Balance | $ / shares $ 30.53
Weighted-Average Grant Date Fair Value, Released | $ / shares 204.60
Weighted-Average Grant Date Fair Value, Ending Balance | $ / shares $ 28.99