Schedule of Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2016

Valuation And Qualifying Accounts [Abstract]

Schedule Of Valuation And Qualifying Accounts Disclosure [Text Block]

	Schedule II - Valuation Accounts
				Additions
			Balance at				Balance at
			Beginning	Charges to			End of
(in thousands)			of Period	Operations	Other	Deductions	Period
	Year ended December 31, 2016:
		Allowance for doubtful accounts(1)	$ 3,417	—	—	579	2,838
	Year ended December 31, 2015:
		Allowance for doubtful accounts(1)	$ 2,943	499	—	25	3,417
	Year ended December 31, 2014:
		Allowance for doubtful accounts(1)	$ 338	2,639	—	34	2,943
(1)		Deductions in the allowance for doubtful accounts represent write-offs, net of recoveries, of amounts
		determined to be uncollectible.