Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended									12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Revenue from Contract with Customer, Excluding Assessed Tax	$ 189,486	$ 199,355	$ 207,609	$ 212,712	$ 216,733		$ 217,415	$ 217,142	$ 224,992	$ 809,162	$ 876,282	$ 839,419
Net income per share - diluted (in dollars per share)	$ 0.39	$ 0.63	$ 0.69	$ 0.78	$ 0.83		$ (0.03)	$ 0.67	$ 0.33	$ 2.50	$ 1.80	$ 0.95
Earnings Per Share, Basic	$ 0.39	$ 0.64	$ 0.70	$ 0.79	$ 0.84		$ (0.03)	$ 0.68	$ 0.33	$ 2.53	$ 1.83	$ 0.97
Net income (loss)	$ 9,244	$ 15,250	$ 16,599	$ 18,579	$ 19,741	[1]	$ (782)	$ 15,912	$ 7,706
Income from operations	16,664	20,886	25,231	27,043	24,468		6,646	24,825	13,503	$ 89,824	$ 69,442	$ 68,331
Gross profit	$ 66,209	$ 67,872	$ 73,493	$ 75,612	$ 76,045		$ 73,405	$ 75,900	$ 79,647	$ 283,186	$ 304,997	$ 285,061

[1] .     Selected Quarterly Financial Data (Unaudited)
Below is selected quarterly financial data for fiscal 2020 and 2019:
    Three Months Ended     June 30, 2019   September 30, 2019   December 31, 2019   March 31, 2020 Net sales   $ 212,712
  $ 207,609
  $ 199,355
  $ 189,486
Gross profit   75,612
  73,493
  67,872
  66,209
Income from operations   27,043
  25,231
  20,886
  16,664
Net income (loss)   $ 18,579
  $ 16,599
  $ 15,250
  $ 9,244
                                    Net income (loss) per share – basic   $ 0.79
  $ 0.70
  $ 0.64
  $ 0.39
                  Net income (loss) per share – diluted   $ 0.78
  $ 0.69
  $ 0.63
  $ 0.39


    Three Months Ended     June 30, 2018   September 30, 2018   December 31, 2018   March 31, 2019 Net sales   $ 224,992
  $ 217,142
  $ 217,415
  $ 216,733
Gross profit   79,647
  75,900
  73,405
  76,045
Income from operations   13,503
  24,825
  6,646
  24,468
Net income (loss)   $ 7,706
  $ 15,912
  $ (782 )   $ 19,741
                                    Net income (loss) per share – basic   $ 0.33
  $ 0.68
  $ (0.03 )   $ 0.84
                  Net income (loss) per share – diluted   $ 0.33
  $ 0.67
  $ (0.03 )   $ 0.83