OTHER CURRENT AND NONCURRENT ASSETS: (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Other current assets
Prepaid expenses and other	$ 7,973	$ 6,622
Assets of non-qualified retirement plan	15,223	13,551
Other current assets	23,196	20,173
Other noncurrent assets
Acquired intangible assets, net	28,969	33,922
Other miscellaneous noncurrent assets	7,512	3,932
Other assets, net	$ 36,481	$ 37,854