Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year		$ 1,485	$ 1,036	$ 1,099
Additions Charged to Costs and Expenses		982	1,113	462
Deductions	[1]	1,050	664	525
Balance at End of Year		1,417	$ 1,485	$ 1,036
Valuation Allowance of Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Additions Charged to Costs and Expenses		29,719
Balance at End of Year		$ 29,719

[1] Notes and accounts receivable written off as uncollectible.