Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands		Dec. 31, 2018	Mar. 31, 2018
Current assets:
Cash and cash equivalents		$ 234,359
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		237,493	$ 286,846
Accounts receivable, net	[1]	147,848	146,561
Inventories, net		233,337	204,386
Prepaid expenses and other current assets		40,294	41,160
Total current assets	[1]	655,838	678,953
Noncurrent Assets:
Property, plant and equipment, net of accumulated depreciation of $867,313 and $866,614 as of December 31, 2018 and March 31, 2018, respectively		438,265	405,316
Goodwill		40,294	40,294
Intangible assets, net		55,170	59,907
Equity method investments		12,861	12,016
Equity method investments		11,722	13,837
Other assets	[1]	17,107	12,600
Total assets	[1]	1,231,257	1,222,923
Current liabilities:
Current portion of long-term debt		28,416	20,540
Accounts payable		144,418	139,989
Accrued expenses	[1]	98,279	125,119
Income taxes payable		3,684	2,010
Total current liabilities	[1]	274,797	287,658
Liabilities, Noncurrent [Abstract]
Long-term debt		277,260	304,083
Other non-current obligations	[1]	125,856	152,249
Deferred Tax Liabilities, Net, Noncurrent	[1]	14,911	15,058
Liabilities	[1]	692,824	759,048
Stockholders’ equity:
Preferred stock, par value $0.01, authorized 10,000 shares, none issued		0	0
Common stock, par value $0.01, authorized 175,000 shares, issued 57,819 and 56,641 shares at December 31, 2018 and March 31, 2018, respectively		578	566
Additional paid-in capital		462,882	462,737
Retained earnings (deficit)	[1]	113,664	3,370
Accumulated other comprehensive income (loss)	[1]	(38,691)	(2,798)
Total stockholders’ equity	[1]	538,433	463,875
Total liabilities and stockholders’ equity	[1]	$ 1,231,257	$ 1,222,923

[1] Period ended March 31, 2018 adjusted due to the adoption of Accounting Standard Codification (“ASC”) 606, Revenue from Contracts with Customers (“ASC 606”). Refer to Note 1, “Basis of Financial Statement Presentation.”