Revenue from Contracts with Customers Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 1,389,877	$ 1,292,861
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,278,193	1,172,630
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	111,684	120,231
Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	1,230,830	1,135,096
Domestic Segment | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,135,982	1,028,495
Domestic Segment | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	94,848	106,601
International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	159,047	157,765
International Segment [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	142,211	144,135
International Segment [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	16,836	13,630
Sales Revenue, Licensed Software, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	154,477	134,819
Sales Revenue, Licensed Software, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	140,445	124,094
Sales Revenue, Licensed Software, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	14,032	10,725
Sales Revenue, Technology Resale, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	55,540	63,376
Sales Revenue, Technology Resale, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	49,158	58,249
Sales Revenue, Technology Resale, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	6,382	5,127
Sales Revenue, Subscriptions, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	84,291	76,636
Sales Revenue, Subscriptions, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	77,702	69,852
Sales Revenue, Subscriptions, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	6,589	6,784
Sales Revenue, Professional Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	490,439	441,268
Sales Revenue, Professional Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	437,229	379,844
Sales Revenue, Professional Services, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	53,210	61,424
Sales Revenue, Managed Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	304,393	268,305
Sales Revenue, Managed Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	277,325	246,145
Sales Revenue, Managed Services, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	27,068	22,160
Sales Revenue, Support and Maintenance Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	276,963	284,564
Sales Revenue, Support and Maintenance Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	226,481	234,236
Sales Revenue, Support and Maintenance Services, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	50,482	50,328
Sales Revenue, Reimbursement Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	23,774	23,893
Sales Revenue, Reimbursement Revenue [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	22,490	22,676
Sales Revenue, Reimbursement Revenue [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 1,284	$ 1,217