Revenue from Contracts with Customers Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 1,429,428	$ 1,340,073	$ 4,250,366	$ 4,000,661
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,298,487	1,215,623	3,849,285	3,595,393
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	130,941	124,450	401,081	405,268
Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	1,265,263	1,188,154	3,762,205	3,525,314
Domestic Segment | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,143,470	1,078,029	3,403,965	3,169,402
Domestic Segment | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	121,793	110,125	358,240	355,912
International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	164,165	151,919	488,161	475,347
International Segment [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	155,017	137,594	445,320	425,991
International Segment [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	9,148	14,325	42,841	49,356
Revenue, Licensed Software, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	154,533	139,888	506,123	447,095
Revenue, Licensed Software, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	144,599	132,447	466,105	417,761
Revenue, Licensed Software, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	9,934	7,441	40,018	29,334
Revenue, Technology Resale, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	70,175	60,378	186,450	199,011
Revenue, Technology Resale, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	65,103	51,097	169,112	171,135
Revenue, Technology Resale, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	5,072	9,281	17,338	27,876
Revenue, Subscriptions, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	91,904	79,115	265,965	238,702
Revenue, Subscriptions, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	85,230	73,792	246,505	220,063
Revenue, Subscriptions, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	6,674	5,323	19,460	18,639
Revenue, Professional Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	507,455	456,725	1,483,201	1,345,311
Revenue, Professional Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	446,562	400,695	1,313,701	1,168,079
Revenue, Professional Services, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	60,893	56,030	169,500	177,232
Revenue, Managed Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	302,435	302,000	904,479	855,857
Revenue, Managed Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	272,933	278,019	818,818	785,951
Revenue, Managed Services, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	29,502	23,981	85,661	69,906
Revenue, Support and Maintenance Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	277,294	277,780	830,668	841,300
Revenue, Support and Maintenance Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	227,131	229,202	679,214	693,217
Revenue, Support and Maintenance Services, Net [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	50,163	48,578	151,454	148,083
Revenue, Reimbursement Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	25,632	24,187	73,480	73,385
Revenue, Reimbursement Revenue [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	23,705	22,902	68,750	69,108
Revenue, Reimbursement Revenue [Member] | International Segment [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 1,927	$ 1,285	$ 4,730	$ 4,277