OTHER CURRENT AND NONCURRENT ASSETS: (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Mar. 31, 2018
Other current assets
Prepaid expenses and other	$ 13,660	$ 6,622
Assets of non-qualified retirement plan	13,706	13,551
Other current assets	27,366	20,173
Other noncurrent assets
Acquired intangible assets, net	26,562	33,922
Other miscellaneous noncurrent assets	7,998	3,932
Other assets, net	$ 34,560	$ 37,854