Accumulated Other Comprehensive Income (Loss) Components of Net of Tax (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2013	$ (22,680)
Foreign currency translation	(3,762)	(1,929)
Unrealized loss on investments	21	1,293
Change in fair value of cash flow hedges	6,322	(319)
Amount reclassified from AOCI	4,410	5,269
Balance as of June 30, 2013	(20,099)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2013	(22,680)
Foreign currency translation	(3,762)
Unrealized loss on investments	21
Change in fair value of cash flow hedges	1,912
Change in postretirement benefit obligations	0
Amount reclassified from AOCI	4,410
Other comprehensive income (loss)	2,581
Balance as of June 30, 2013	(20,099)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2013	(30,153)
Foreign currency translation	(3,762)
Other comprehensive income (loss)	(3,762)
Balance as of June 30, 2013	(33,915)
Unrealized Gain (Loss) on Investments
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2013	39,645
Unrealized loss on investments	21
Other comprehensive income (loss)	21
Balance as of June 30, 2013	39,666
Fair Market Value of Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2013	(32,298)
Change in fair value of cash flow hedges	1,912
Amount reclassified from AOCI	4,410
Other comprehensive income (loss)	6,322
Balance as of June 30, 2013	(25,976)
Postretirement Benefit Obligation Gain (Loss)
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2013	126
Change in postretirement benefit obligations	0
Other comprehensive income (loss)	0
Balance as of June 30, 2013	$ 126