Goodwill and Other Intangible Assets, Net (Amortization Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 24,700	$ 20,400	$ 19,300
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2018	22,764
2019	22,313
2020	22,313
2021	19,790
2022	18,146
Thereafter	104,813
Finite-lived intangible assets	$ 210,139
Facility management contracts
Finite-Lived Intangible Assets [Line Items]
Weighted average period before renewal or extension	1 year 6 months 20 days
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Finite-lived intangible assets	$ 201,794	$ 145,880