Revenue from Contracts with Customers Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 1,340,073	$ 1,276,007	$ 4,000,661	$ 3,828,487
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,215,623		3,595,393
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	124,450		405,268
Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	1,188,154	1,133,971	3,525,314	3,421,429
Domestic Segment | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,078,029		3,169,402
Domestic Segment | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	110,125		355,912
Global Segment
Disaggregation of Revenue [Line Items]
Revenues	151,919	142,036	475,347	407,058
Global Segment | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	137,594		425,991
Global Segment | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	14,325		49,356
Sales Revenue, Licensed Software, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	139,888	144,515	447,095	442,729
Sales Revenue, Licensed Software, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	132,447	133,339	417,761	412,766
Sales Revenue, Licensed Software, Net [Member] | Global Segment
Disaggregation of Revenue [Line Items]
Revenues	7,441	11,176	29,334	29,963
Sales Revenue, Technology Resale, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	60,378	56,946	199,011	194,185
Sales Revenue, Technology Resale, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	51,097	49,793	171,135	176,664
Sales Revenue, Technology Resale, Net [Member] | Global Segment
Disaggregation of Revenue [Line Items]
Revenues	9,281	7,153	27,876	17,521
Sales Revenue, Subscriptions, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	79,115	122,560	238,702	354,771
Sales Revenue, Subscriptions, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	73,792	116,144	220,063	336,914
Sales Revenue, Subscriptions, Net [Member] | Global Segment
Disaggregation of Revenue [Line Items]
Revenues	5,323	6,416	18,639	17,857
Sales Revenue, Professional Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	456,725	400,884	1,345,311	1,193,362
Sales Revenue, Professional Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	400,695	354,390	1,168,079	1,050,567
Sales Revenue, Professional Services, Net [Member] | Global Segment
Disaggregation of Revenue [Line Items]
Revenues	56,030	46,494	177,232	142,795
Sales Revenue, Managed Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	302,000	263,584	855,857	785,082
Sales Revenue, Managed Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	278,019	243,454	785,951	728,760
Sales Revenue, Managed Services, Net [Member] | Global Segment
Disaggregation of Revenue [Line Items]
Revenues	23,981	20,130	69,906	56,322
Sales Revenue, Support and Maintenance Services, Net [Member]
Disaggregation of Revenue [Line Items]
Revenues	277,780	263,361	841,300	785,039
Sales Revenue, Support and Maintenance Services, Net [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	229,202	213,728	693,217	646,114
Sales Revenue, Support and Maintenance Services, Net [Member] | Global Segment
Disaggregation of Revenue [Line Items]
Revenues	48,578	49,633	148,083	138,925
Sales Revenue, Reimbursement Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	24,187	24,157	73,385	73,319
Sales Revenue, Reimbursement Revenue [Member] | Domestic Segment
Disaggregation of Revenue [Line Items]
Revenues	22,902	23,123	69,108	69,644
Sales Revenue, Reimbursement Revenue [Member] | Global Segment
Disaggregation of Revenue [Line Items]
Revenues	$ 1,285	$ 1,034	$ 4,277	$ 3,675