Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 1,411,741	$ 1,389,877
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,318,959	1,278,193
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	92,782	111,684
Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	1,246,415	1,230,830
Domestic Segment | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,165,515	1,135,982
Domestic Segment | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	80,900	94,848
International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	165,326	159,047
International Segment [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	153,444	142,211
International Segment [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	11,882	16,836
Sales Revenue, Licensed Software, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	158,032	154,477
Sales Revenue, Licensed Software, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	146,497	140,445
Sales Revenue, Licensed Software, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	11,535	14,032
Sales Revenue, Technology Resale, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	51,487	55,540
Sales Revenue, Technology Resale, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	44,449	49,158
Sales Revenue, Technology Resale, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	7,038	6,382
Sales Revenue, Subscriptions, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	94,385	84,291
Sales Revenue, Subscriptions, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	86,936	77,702
Sales Revenue, Subscriptions, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	7,449	6,589
Sales Revenue, Professional Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	511,346	490,439
Sales Revenue, Professional Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	452,784	437,229
Sales Revenue, Professional Services, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	58,562	53,210
Sales Revenue, Managed Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	309,354	304,393
Sales Revenue, Managed Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	279,736	277,325
Sales Revenue, Managed Services, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	29,618	27,068
Sales Revenue, Support and Maintenance Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	273,681	276,963
Sales Revenue, Support and Maintenance Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	223,416	226,481
Sales Revenue, Support and Maintenance Services, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	50,265	50,482
Sales Revenue, Reimbursement Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	13,456	23,774
Sales Revenue, Reimbursement Revenue [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	12,597	22,490
Sales Revenue, Reimbursement Revenue [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 859	$ 1,284