Goodwill and Other Intangible Assets, Net (Intangible Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Amortization period	1 year
Schedule of intangible assets
Accumulated Amortization	$ (132,779)	$ (108,152)
Finite-lived intangible assets	210,139
Intangible assets, gross carrying amount	388,118	312,036
Total acquired intangible assets, Net carrying amount	255,339	203,884
Trade names
Schedule of intangible assets
Indefinite lived intangible assets	$ 45,200	45,200
Facility management contracts
Goodwill [Line Items]
Amortization period	16 years 3 months
Schedule of intangible assets
Gross Carrying Amount	$ 308,518	233,136
Accumulated Amortization	(106,724)	(87,256)
Finite-lived intangible assets	201,794	145,880
Covenants not to compete
Schedule of intangible assets
Gross Carrying Amount	700	0
Accumulated Amortization	(517)	0
Finite-lived intangible assets	$ 183	0
Technology
Goodwill [Line Items]
Amortization period	7 years 3 months
Schedule of intangible assets
Gross Carrying Amount	$ 33,700	33,700
Accumulated Amortization	(25,538)	(20,896)
Finite-lived intangible assets	$ 8,162	$ 12,804