Annual report pursuant to Section 13 and 15(d)

Recent Accounting Pronouncements (Details)

v3.8.0.1
Recent Accounting Pronouncements (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]      
Excess tax benefit (expense) from stock-based compensation $ 0   $ (1,045)
Shares surrendered in lieu of tax $ 936 $ 1,156 1,033
Accounting Standards Update 2016-09      
New Accounting Pronouncements or Change in Accounting Principle [Line Items]      
Excess tax benefit (expense) from stock-based compensation   0  
Shares surrendered in lieu of tax   $ (1,200) $ (1,000)