Schedule II - Consolidated Valuation and Qualifying Accounts (Details 2) - Allowance for Doubtful Accounts [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts:
Balance, beginning of period		$ 9,835	$ 9,511	$ 10,085
Charged to costs and expenses		8,302	11,343	8,548
Other	[1]	851	1,012	1,335
Deductions	[2]	8,509	12,031	10,457
Balance, end of period		$ 10,479	$ 9,835	$ 9,511

[1] Recoveries.

[2] Uncollectible accounts written off.