SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in Valuation Allowances and Reserves [Roll Forward]
Benefit (charge) within operating expense	$ (9,000)	$ (4,000)	$ 14,000
Accounts receivable allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	15,560	16,388	16,955
Charged to Earnings	13,118	11,172	7,086
Transferred from (to) Other Accounts	0	0	0
Deductions	13,763	12,000	7,653
Balance at End of Period	14,915	15,560	16,388
Direct finance lease allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	243	288	501
Charged to Earnings	396	1,495	47
Transferred from (to) Other Accounts	0	0	0
Deductions	391	1,540	260
Balance at End of Period	248	243	288
Self-insurance accruals
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	311,821	300,994	290,255
Charged to Earnings	337,554	308,026	273,509
Transferred from (to) Other Accounts	71,703	68,999	62,548
Deductions	384,177	366,198	325,318
Balance at End of Period	336,901	311,821	300,994
Valuation allowance on deferred tax assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	14,991	24,742	33,793
Charged to Earnings	98	(1,150)	(976)
Transferred from (to) Other Accounts	0	0	0
Deductions	(1,298)	8,601	8,075
Balance at End of Period	$ 16,387	$ 14,991	$ 24,742