REVENUE - Revenue Stream (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 227,375	$ 205,592	$ 492,966	$ 418,138
Revenue recognized at a point in time
Disaggregation of Revenue [Line Items]
Revenue	53,323	44,274	147,239	107,538
Revenue recognized over time
Disaggregation of Revenue [Line Items]
Revenue	174,052	161,318	345,727	310,600
Perpetual license | Revenue recognized at a point in time
Disaggregation of Revenue [Line Items]
Revenue	9,057	19,320	12,716	34,270
Term license | Revenue recognized at a point in time
Disaggregation of Revenue [Line Items]
Revenue	44,266	24,954	134,523	73,268
Maintenance
Disaggregation of Revenue [Line Items]
Revenue	72,222	69,329	145,917	137,035
Maintenance | Revenue recognized over time
Disaggregation of Revenue [Line Items]
Revenue	72,222	69,329	145,917	137,035
Subscription
Disaggregation of Revenue [Line Items]
Revenue	165,326	125,982	372,744	269,760
Pega Cloud
Disaggregation of Revenue [Line Items]
Revenue	48,838	31,699	92,304	59,457
Pega Cloud | Revenue recognized over time
Disaggregation of Revenue [Line Items]
Revenue	48,838	31,699	92,304	59,457
Consulting
Disaggregation of Revenue [Line Items]
Revenue	52,992	60,290	107,506	114,108
Consulting | Revenue recognized over time
Disaggregation of Revenue [Line Items]
Revenue	$ 52,992	$ 60,290	$ 107,506	$ 114,108