CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 24, 2016	Sep. 26, 2015	Sep. 24, 2016	Sep. 26, 2015
Income Statement [Abstract]
Service revenue	$ 292,849	$ 222,506	$ 806,397	$ 633,666
Product revenue	132,871	126,959	408,246	375,786
Total revenue	425,720	349,465	1,214,643	1,009,452
Costs and expenses:
Cost of services provided (excluding amortization of intangible assets)	200,118	145,165	543,588	425,614
Cost of products sold (excluding amortization of intangible assets)	69,332	66,225	204,270	193,320
Selling, general and administrative	85,650	76,225	269,067	218,953
Amortization of intangible assets	11,825	6,410	29,390	17,385
Operating income	58,795	55,440	168,328	154,180
Other income (expense):
Interest income	523	177	1,008	758
Interest expense	(7,079)	(3,851)	(20,199)	(11,251)
Other income (expense), net	1,017	1,390	10,059	1,749
Income from continuing operations, before income taxes	53,256	53,156	159,196	145,436
Provision for income taxes	15,565	15,255	48,385	26,662
Income from continuing operations, net of income taxes	37,691	37,901	110,811	118,774
Income (loss) from discontinued operations, net of income taxes	342	(34)	328	(48)
Net income	38,033	37,867	111,139	118,726
Less: Net income attributable to noncontrolling interests	298	488	1,054	1,297
Net income attributable to common shareholders	$ 37,735	$ 37,379	$ 110,085	$ 117,429
Basic:
Continuing operations attributable to common shareholders (in dollars per share)	$ 0.79	$ 0.81	$ 2.34	$ 2.52
Discontinued operations (in dollars per share)	0.01	0.00	0.00	0.00
Net income attributable to common shareholders (in dollars per share)	0.80	0.81	2.34	2.52
Diluted:
Continuing operations attributable to common shareholders (in dollars per share)	0.78	0.79	2.29	2.47
Discontinued operations (in dollars per share)	0.01	0.00	0.01	0.00
Net income attributable to common shareholders (in dollars per share)	$ 0.79	$ 0.79	$ 2.30	$ 2.47