Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Operating Activities:
Net income (loss)	$ 202,329	$ (26,910)
Adjustment to reconcile net income (loss) to net cash from operating activities:
Depreciation and amortization	65,109	38,258
Stock-based compensation expense	3,098	2,527
Deferred income taxes	7,321	40,666
Loss on disposal of property and equipment	278	60
Loss from equity-method investments	107
Changes in operating assets and liabilities, excluding acquisitions:
Accounts receivable	29,791	(3,499)
Inventories	(87,461)	28,152
Accounts payable and accrued expenses	(4,474)	(55,523)
Income taxes payable	(33,345)	81,159
Other assets	(30,271)	36,297
Other liabilities	44,515	19,763
Net cash provided by operating activities	196,997	160,950
Investing Activities:
Purchases of property and equipment	(94,083)	(65,249)
Purchase of business, net of cash and debt acquired	(12,317)	(150,277)
Purchases of investment securities	(1,102,776)	(1,476,235)
Redemptions of investment securities	881,372	1,466,490
Other investing activities	(950)	(959)
Net cash used in investing activities	(328,754)	(226,230)
Financing Activities:
Dividends paid	(58,196)	(56,359)
Proceeds from exercise of stock options	3,515	4,369
Purchase of treasury stock	(811)
Principle payments of debt	(1,893)
Payments of tax withholdings for vested restricted stock units	(790)	(498)
Net cash used in financing activities	(58,175)	(52,488)
Effect of exchange rate on cash	(3,265)	3,307
Decrease in cash and cash equivalents	(193,197)	(114,461)
Cash and cash equivalents at beginning of period	547,415	578,634
Cash and cash equivalents at end of period	$ 354,218	$ 464,173