(Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Numerator
Net income	$ 27,995	$ 21,293	$ 85,971	$ 54,488
Denominator
Denominator for basic earnings per share — weighted average shares outstanding	52,824	52,278	52,727	52,110
Dilutive effect of unvested restricted stock units and options issued to employees and directors	379	452	379	512
Denominator for diluted earnings per share (in shares)	53,203	52,730	53,106	52,622
Earnings per Common Share:
Basic net earnings per share (in USD per share)	$ 0.53	$ 0.41	$ 1.63	$ 1.05
Diluted net earnings per share (in USD per share)	$ 0.53	$ 0.40	$ 1.62	$ 1.04