Income Tax Expense Unrecognized Tax Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Mar. 31, 2011
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Effective Income Tax Rate, Continuing Operations	34.10%	34.30%	34.40%	36.60%
Unrecognized Tax Benefits					$ 9,594
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	1,400		1,400		4,975
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Upper Bound	6,019		6,019
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	877		877
Income Tax Examination, Interest Accrued	946		946
Income Tax Examination, Penalties Accrued	$ 81		$ 81