CONSOLIDATED STATEMENTS OF EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock $.01 Par Value	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Parent [Member]
Balance at Mar. 31, 2012	$ 520,305	$ 0	$ 0	$ 0	$ 279	$ 0
Balance (in shares) at Mar. 31, 2012		0
Parent company investment							532,301
Increase (Decrease) in Stockholders' Equity
Comprehensive income	64,012			0	(680)		64,692
Net transfers (to) from parent	(52,417)						(52,417)
Dividends	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	64,012
Balance at Mar. 31, 2013	531,900	0	0	0	(401)	0
Balance (in shares) at Mar. 31, 2013		0
Parent company investment	872,236						872,236
Increase (Decrease) in Stockholders' Equity
Comprehensive income	132,153			0	(1,104)		133,257
Issuance of common stock in connection with spin-off	63,875,000
Net transfers (to) from parent	206,678						206,678
Dividends	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	132,153
Balance at Mar. 31, 2014	870,731	0	0	0	(1,505)	0
Balance (in shares) at Mar. 31, 2014		0
Parent company investment	0						0
Increase (Decrease) in Stockholders' Equity
Comprehensive income	30,992			19,384	(48,536)		60,144
Issuance of common stock in connection with spin-off	63,875,000	63,875,472
Common Stock, Value, Issued	639	639
Net transfers (to) from parent	16,181						16,181
Restricted stock grants			(7,299)			7,299
Restricted stock grants (in shares)		180,095
Share-based compensation	3,012		3,012
Restricted stock units vested and issued during the period		123,208
Stock issued during the period, value, restricted units vested	(2,301)		(5,280)			2,979
Treasury stock purchased	(6,870)					(6,870)
Treasury stock purchased (in shares)		(162,000)
Employee benefit plans and other	(6,489)	0	0			(6,489)
Employee benefit plans and other (in shares)		(138,276)
Dividends	(214,000)						(214,000)
Proceeds from Contributions from Parent	956,869		1,751,692
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	30,992				(60,262)
Proceeds from Partnership Contribution							(734,561)
Balance at Mar. 31, 2015	$ 1,648,764	$ 639	$ 1,742,125	$ 19,384	$ (110,303)	$ (3,081)
Balance (in shares) at Mar. 31, 2015		63,878,499