Quarterly report pursuant to Section 13 or 15(d)

Basis of Financial Statement Presentation - ASC 606 Adjustment Statement of Operations (Details)

v3.10.0.1
Basis of Financial Statement Presentation - ASC 606 Adjustment Statement of Operations (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 6 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax $ 349,233 $ 301,568 $ 676,849 $ 575,514
Operating costs and expenses:        
Cost of sales 235,668 216,664 468,463 416,493
Research and development 10,995 9,536 21,683 18,783
Operating Income (Loss) 50,000 31,597 85,176 59,204
Income tax expense 2,000 2,864 6,600 4,004
Net income (loss) $ 37,141 $ 12,819 $ 72,361 $ 233,258
Net income (loss) per basic share (in usd per share) $ 0.64 $ 0.26 $ 1.26 $ 4.80
Earnings Per Share, Diluted $ 0.63 $ 0.22 $ 1.22 $ 4.01
As Previously Reported        
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax   $ 301,471   $ 575,471
Operating costs and expenses:        
Cost of sales   216,395   415,958
Research and development   9,662   19,052
Operating Income (Loss)   31,643   59,427
Income tax expense   2,880   4,030
Net income (loss)   12,849   $ 233,455
Net income (loss) per basic share (in usd per share)       $ 4.02
ASC 606 Adjustments | ASC 606 Adjustments        
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax   97   $ 43
Operating costs and expenses:        
Cost of sales   269   535
Research and development   (126)   (269)
Operating Income (Loss)   (46)   (223)
Income tax expense   (16)   (26)
Net income (loss)   $ (30)   $ (197)
Net income (loss) per basic share (in usd per share)       $ (0.01)