Schedule II-Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance For Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 12,619	$ 9,248	$ 6,728
“Additions” Charged to Costs and Expenses	8,769	11,480	9,421
“Other” Additions (Deductions)	0	0	0
“Less” Deductions	9,659	8,109	6,901
Balance at End of Year	11,729	12,619	9,248
Insurance Reserves [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	31,137	30,880	25,188
“Additions” Charged to Costs and Expenses	54,341	52,858	52,658
“Other” Additions (Deductions)	0	0	0
“Less” Deductions	53,657	52,601	46,966
Balance at End of Year	$ 31,821	$ 31,137	$ 30,880