CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
OPERATING ACTIVITIES
Net income	$ 264,308	$ 114,394	$ 5,710
Reconciliation of net income to cash provided by operating activities:
Depreciation, amortization and accretion	44,941	48,572	52,628
Amortization on debt issuance costs	286	375	375
Loss on extinguishment of debt	447	0	0
Bad debt expense	2,849	4,168	2,847
Deferred tax expense (benefit)	6,939	8,138	(24,495)
Stock-based compensation	14,585	14,157	6,011
Employee stock purchase plan	189	150	164
Loss on disposal of property and equipment	277	387	538
Impairment of goodwill	0	0	113,944
Impairment of intangible and other long-lived assets	180	2,417	13,222
Restructuring charges	295	1,667	28,984
Changes in operating assets and liabilities:
Trade accounts receivable, net	(16,157)	10,770	(1,336)
Inventories, net	8,827	(751)	1,060
Prepaid expenses and other current assets	(515)	11,124	7,975
Income tax receivable	(165)	26,999	(1,331)
Other assets	2,344	(2,090)	1,882
Trade accounts payable	31,035	(2,184)	(7,825)
Accrued expenses	(7,160)	28,627	(403)
Income taxes payable	3,809	(1,693)	(3,643)
Long-term liabilities	2,191	62,128	3,023
Net cash provided by operating activities	359,505	327,355	199,330
INVESTING ACTIVITIES
Purchases of property and equipment	(29,086)	(34,813)	(44,499)
Proceeds from sale of property and equipment, net	68	116	0
Net cash used in investing activities	(29,018)	(34,697)	(44,499)
FINANCING ACTIVITIES
Proceeds from short-term borrowings	162,001	214,751	405,988
Repayments of short-term borrowings	(161,621)	(214,889)	(468,938)
Debt issuance costs on short-term borrowings	(1,297)	0	0
Proceeds on issuance of stock for employee stock purchase plan	1,024	765	798
Cash paid for repurchase of common stock	(161,395)	(149,687)	(12,572)
Cash paid for shares withheld for taxes	(5,328)	(8,105)	(8,452)
Contingent consideration paid	0	0	(20,058)
Repayment of mortgage principal	(578)	(550)	(523)
Net cash used in financing activities	(167,194)	(157,715)	(103,757)
Effect of foreign currency exchange rates on cash	(3,571)	3,263	(5,266)
Net change in cash and cash equivalents	159,722	138,206	45,808
Cash and cash equivalents at beginning of period	429,970	291,764	245,956
Cash and cash equivalents at end of period	589,692	429,970	291,764
Cash paid during the period for
Income taxes, net of refunds of $3,824, $23,133 and $17,132, as of March 31, 2019, 2018 and 2017, respectively	53,657	14,407	14,099
Interest	3,811	3,774	5,494
Non-cash investing and financing activities:
Accrued for purchases of property and equipment	1,789	2,020	1,101
Accrued for asset retirement obligations	4,706	1,359	2,359
Accrued for shares withheld for taxes	$ 0	$ 171	$ 0