CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Net revenues	$ 216,183	$ 215,017	$ 439,289	$ 421,375
Cost of revenues	105,737	104,047	215,770	203,047
Gross profit	110,446	110,970	223,519	218,328
Operating expenses:
Research, development, and engineering	22,379	22,609	44,723	45,803
Selling, general, and administrative	56,875	54,296	112,662	109,974
(Gain) loss, net from litigation settlements	(349)	(31)	4,390	(907)
Restructuring and other related charges/adjustments	(415)	0	(1,463)	0
Total operating expenses	78,490	76,874	160,312	154,870
Operating income	31,956	34,096	63,207	63,458
Interest expense	(7,257)	(7,320)	(14,545)	(10,061)
Other non-operating income and (expense), net	1,340	(2,138)	3,692	(2,423)
Income before income taxes	26,039	24,638	52,354	50,974
Income tax expense	5,565	6,742	11,493	11,850
Net income	$ 20,474	$ 17,896	$ 40,861	$ 39,124
Earnings per common share:
Basic (in dollars per share)	$ 0.63	$ 0.53	$ 1.27	$ 1.09
Diluted (in dollars per share)	$ 0.63	$ 0.52	$ 1.24	$ 1.07
Shares used in computing basic earnings per common share	32,281	33,590	32,269	35,796
Shares used in computing diluted earnings per common share	32,726	34,245	32,865	36,676
Cash dividends declared per common share (in dollars per share)	$ 0.15	$ 0.15	$ 0.30	$ 0.30