REVENUE - Revenue Stream (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 256,268	$ 225,951	$ 895,469	$ 718,917
Revenue recognized over time
Disaggregation of Revenue [Line Items]
Revenue	217,973	186,167	623,321	531,894
Revenue recognized at a point in time
Disaggregation of Revenue [Line Items]
Revenue	38,295	39,784	272,148	187,023
Pega Cloud
Disaggregation of Revenue [Line Items]
Revenue	78,369	54,776	219,520	147,080
Pega Cloud | Revenue recognized over time
Disaggregation of Revenue [Line Items]
Revenue	78,369	54,776	219,520	147,080
Client Cloud
Disaggregation of Revenue [Line Items]
Revenue	118,609	110,602	488,757	391,042
Maintenance
Disaggregation of Revenue [Line Items]
Revenue	83,188	74,670	237,531	220,587
Maintenance | Revenue recognized over time
Disaggregation of Revenue [Line Items]
Revenue	83,188	74,670	237,531	220,587
Term license | Revenue recognized at a point in time
Disaggregation of Revenue [Line Items]
Revenue	35,421	35,932	251,226	170,455
Consulting
Disaggregation of Revenue [Line Items]
Revenue	56,416	56,721	166,270	164,227
Consulting | Revenue recognized over time
Disaggregation of Revenue [Line Items]
Revenue	56,416	56,721	166,270	164,227
Cloud subscription
Disaggregation of Revenue [Line Items]
Revenue	196,978	165,378	708,277	538,122
Perpetual license | Revenue recognized at a point in time
Disaggregation of Revenue [Line Items]
Revenue	$ 2,874	$ 3,852	$ 20,922	$ 16,568