Revenue Recognition - Summary of Revenue from Prepaid Gift Cards Expected to be Recognized in Future Related to Performance Obligation Unsatisfied or Partially Satisfied (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Disaggregation Of Revenue [Line Items]
Revenue, remaining performance obligation, amount	$ 12,633
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-04-01
Disaggregation Of Revenue [Line Items]
Revenue, remaining performance obligation, amount	$ 10,665
Revenue, remaining performance obligation, expected timing of satisfaction, period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Disaggregation Of Revenue [Line Items]
Revenue, remaining performance obligation, amount	$ 1,303
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Disaggregation Of Revenue [Line Items]
Revenue, remaining performance obligation, amount	$ 665
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year