Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 28, 2019	Sep. 30, 2020	Sep. 28, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 1,368,673	$ 1,429,428	$ 4,110,763	$ 4,250,366
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,276,406	1,298,487	3,848,618	3,849,285
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	92,267	130,941	262,145	401,081
Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	1,230,769	1,265,263	3,645,397	3,762,205
Domestic Segment | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,143,515	1,143,470	3,410,827	3,403,965
Domestic Segment | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	87,254	121,793	234,570	358,240
International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	137,904	164,165	465,366	488,161
International Segment [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	132,891	155,017	437,791	445,320
International Segment [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	5,013	9,148	27,575	42,841
Sales Revenue, Licensed Software, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	171,694	154,533	481,888	506,123
Sales Revenue, Licensed Software, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	159,327	144,599	444,774	466,105
Sales Revenue, Licensed Software, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	12,367	9,934	37,114	40,018
Sales Revenue, Technology Resale, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	47,113	70,175	140,717	186,450
Sales Revenue, Technology Resale, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	45,217	65,103	126,042	169,112
Sales Revenue, Technology Resale, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,896	5,072	14,675	17,338
Sales Revenue, Subscriptions, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	93,407	91,904	279,844	265,965
Sales Revenue, Subscriptions, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	87,878	85,230	260,095	246,505
Sales Revenue, Subscriptions, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	5,529	6,674	19,749	19,460
Sales Revenue, Professional Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	479,895	507,455	1,452,323	1,483,201
Sales Revenue, Professional Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	433,127	446,562	1,295,759	1,313,701
Sales Revenue, Professional Services, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	46,768	60,893	156,564	169,500
Sales Revenue, Managed Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	311,844	302,435	928,356	904,479
Sales Revenue, Managed Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	280,827	272,933	836,242	818,818
Sales Revenue, Managed Services, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	31,017	29,502	92,114	85,661
Sales Revenue, Support and Maintenance Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	259,978	277,294	807,695	830,668
Sales Revenue, Support and Maintenance Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	219,682	227,131	663,399	679,214
Sales Revenue, Support and Maintenance Services, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	40,296	50,163	144,296	151,454
Sales Revenue, Reimbursement Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	4,742	25,632	19,940	73,480
Sales Revenue, Reimbursement Revenue [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	4,711	23,705	19,086	68,750
Sales Revenue, Reimbursement Revenue [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 31	$ 1,927	$ 854	$ 4,730