Derivative Instruments and Hedging Activities (Details)	3 Months Ended
	Jun. 30, 2012 USD ($)	Jun. 30, 2011 USD ($)	Jun. 30, 2012 United Kingdom, Pounds	Jun. 30, 2012 United Kingdom, Pounds Foreign Exchange Forward [Member] USD ($)	Jun. 30, 2012 United Kingdom, Pounds Foreign Exchange Forward [Member] GBP (£)	Jun. 30, 2012 Canada, Dollars USD ($)	Jun. 30, 2012 Canada, Dollars Foreign Exchange Forward [Member] USD ($)	Jun. 30, 2012 Canada, Dollars Foreign Exchange Forward [Member] CAD	Jun. 30, 2012 Other Assets [Member] Foreign Exchange Forward [Member] USD ($)	Jun. 30, 2012 Accounts Payable and Accrued Liabilities [Member] Foreign Exchange Forward [Member] USD ($)
Derivative [Line Items]
Derivative, average forward exchange rate				1.58		1.01
Notional amount of foreign currency derivatives				$ 52,700,000	£ 33,200,000		$ 21,600,000	21,800,000
Remaining maturity of foreign currency derivatives, maximum			6 years			8 years
Net unrealized gain (loss) on foreign exchange contracts	495,000	36,000
Derivative assets									800,000
Derivative liabilities										$ 200,000