Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Weighted-average shares outstanding for basic and diluted net income per share
Net income (in dollars)	$ 12,945	$ 15,497
Basic net income per share:
Weighted-average shares outstanding - Basic	59,559	59,281
Basic net income per common share (in usd per share)	$ 0.22	$ 0.26
Diluted net income per share:
Weighted-average shares outstanding - Basic	59,559	59,281
Effect of potentially dilutive securities	13	107
Weighted-average shares outstanding - Diluted	59,572	59,388
Diluted net income per common share (in usd per share)	$ 0.22	$ 0.26