Quarterly report pursuant to Section 13 or 15(d)

Recent Accounting Pronouncements (Details)

v3.10.0.1
Recent Accounting Pronouncements (Details) - USD ($)
$ in Thousands
 9 Months Ended
Sep. 30, 2018
Sep. 30, 2018
Jan. 01, 2018
Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]        
Retained earnings $ 2,635,865 $ 2,635,865   $ 2,568,764
Other current assets 2,210 2,210   2,797
Deferred income tax liabilities 961,835 961,835   932,593
Deferred revenue and other current liabilities 6,908 6,908   $ 5,168
Deferred revenue        
Deferred revenue current 6,500 6,500 $ 4,500  
Deferred revenue noncurrent 2,200 2,200 2,300  
Deferred revenue $ 8,700 8,700 6,800  
Revenue recognized   $ 4,000    
Revenue recognized percentage 87.00%      
Practical expedient modified contract   true    
ASU 2014-09 | Adjustment        
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]        
Retained earnings     1,200  
Other current assets     300  
Deferred income tax liabilities     400  
Deferred revenue and other current liabilities     $ (1,300)  
Minimum        
Deferred revenue        
Revenue recognized period 1 year      
Maximum        
Deferred revenue        
Revenue recognized period 3 years