Significant Accounting Policies Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2017	Jun. 30, 2017	Jun. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred Income Tax Expense (Benefit)		$ 300	$ (178)
Accounting Standards Update 2016-16 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax		$ 2,000
Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred Income Tax Expense (Benefit)	$ 4,500