SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION CF (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities			$ 132,476	$ 134,898
Capital expenditures	(160,027)	(26,850)	(339,559)	(113,405)
Proceeds from asset dispositions			155,603	96,376
Proceeds from sale of unconsolidated affiliate			112,210	0
Investment in unconsolidated affiliate			0	(7,153)
Net cash used in investing activities			(71,746)	(24,182)
Proceeds from borrowings			160,146	0
Debt issuance costs			(15,152)	0
Repayment of debt and debt redemption premiums			(117,748)	(24,300)
Dividends paid			(18,138)	(14,297)
Increases (decreases) in cash related to intercompany advances and debt			0	0
Partial prepayment of put/call obligation			(27)	(33)
Issuance of Common Stock			11,550	7,869
Tax benefit related to stock-based compensation			4,234	433
Net cash provided by (used in) financing activities			24,865	(30,328)
Effect of exchange rate changes on cash and cash equivalents			12,303	6,411
Net increase (decrease) in cash and cash equivalents			97,898	86,799
Cash and cash equivalents at beginning of period			215,623	261,550
Cash and cash equivalents at end of period	313,521	348,349	313,521	348,349
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities			(20,277)	(20,075)
Capital expenditures			(11,206)	(8,353)
Proceeds from asset dispositions			0	0
Proceeds from sale of unconsolidated affiliate			0
Investment in unconsolidated affiliate				(7,153)
Net cash used in investing activities			(11,206)	(15,506)
Proceeds from borrowings			157,500
Debt issuance costs			(15,152)
Repayment of debt and debt redemption premiums			(114,806)	(24,300)
Dividends paid			(15,072)	(2,742)
Increases (decreases) in cash related to intercompany advances and debt			(24,615)	112,427
Partial prepayment of put/call obligation			(27)	(33)
Issuance of Common Stock			11,550	7,869
Tax benefit related to stock-based compensation			4,234	433
Net cash provided by (used in) financing activities			3,612	93,654
Effect of exchange rate changes on cash and cash equivalents			0	0
Net increase (decrease) in cash and cash equivalents			(27,871)	58,073
Cash and cash equivalents at beginning of period			31,853	76,609
Cash and cash equivalents at end of period	3,982	134,682	3,982	134,682
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities			46,258	62,030
Capital expenditures			(275,801)	(46,389)
Proceeds from asset dispositions			154,689	35,185
Proceeds from sale of unconsolidated affiliate			0
Investment in unconsolidated affiliate				0
Net cash used in investing activities			(121,112)	(11,204)
Proceeds from borrowings			0
Debt issuance costs			0
Repayment of debt and debt redemption premiums			0	0
Dividends paid			34	(9,755)
Increases (decreases) in cash related to intercompany advances and debt			73,818	(40,697)
Partial prepayment of put/call obligation			0	0
Issuance of Common Stock			0	0
Tax benefit related to stock-based compensation			0	0
Net cash provided by (used in) financing activities			73,852	(50,452)
Effect of exchange rate changes on cash and cash equivalents			0	0
Net increase (decrease) in cash and cash equivalents			(1,002)	374
Cash and cash equivalents at beginning of period			5,370	3,155
Cash and cash equivalents at end of period	4,368	3,529	4,368	3,529
Consolidations, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities			0	0
Capital expenditures			105,863	24,589
Proceeds from asset dispositions			(105,863)	(24,589)
Proceeds from sale of unconsolidated affiliate			0
Investment in unconsolidated affiliate				0
Net cash used in investing activities			0	0
Proceeds from borrowings			0
Debt issuance costs			0
Repayment of debt and debt redemption premiums			0	0
Dividends paid			0	0
Increases (decreases) in cash related to intercompany advances and debt			0	0
Partial prepayment of put/call obligation			0	0
Issuance of Common Stock			0	0
Tax benefit related to stock-based compensation			0	0
Net cash provided by (used in) financing activities			0	0
Effect of exchange rate changes on cash and cash equivalents			0	0
Net increase (decrease) in cash and cash equivalents			0	0
Cash and cash equivalents at beginning of period			0	0
Cash and cash equivalents at end of period	0	0	0	0
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities			106,495	92,943
Capital expenditures			(158,415)	(83,252)
Proceeds from asset dispositions			106,777	85,780
Proceeds from sale of unconsolidated affiliate			112,210
Investment in unconsolidated affiliate				0
Net cash used in investing activities			60,572	2,528
Proceeds from borrowings			2,646
Debt issuance costs			0
Repayment of debt and debt redemption premiums			(2,942)	0
Dividends paid			(3,100)	(1,800)
Increases (decreases) in cash related to intercompany advances and debt			(49,203)	(71,730)
Partial prepayment of put/call obligation			0	0
Issuance of Common Stock			0	0
Tax benefit related to stock-based compensation			0	0
Net cash provided by (used in) financing activities			(52,599)	(73,530)
Effect of exchange rate changes on cash and cash equivalents			12,303	6,411
Net increase (decrease) in cash and cash equivalents			126,771	28,352
Cash and cash equivalents at beginning of period			178,400	181,786
Cash and cash equivalents at end of period	$ 305,171	$ 210,138	$ 305,171	$ 210,138