Investments - Summary of Available-for-Sale Securities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013		Mar. 31, 2012	Mar. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 71,539		$ 19,065		$ 28,065	$ 84,402
Cash, Cash equivalents and Available-for-sale Investments, Amortized Cost	103,548		77,442
Available-for-sale securities, Gross Unrealized Gains	3,455		8,082
Available-for-sale securities, Gross Unrealized Losses	420		48
Cash, Cash equivalents and Available-for-sale Investments, Estimated Fair Value	106,583		85,476
Short-term investments available-for-sale	35,044		66,411
Cash
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	65,867		8,529
Cash and cash equivalents, Estimated Fair Value	65,867		8,529
Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	5,672		10,536
Cash and cash equivalents, Estimated Fair Value	5,672		10,536
U.S Treasury Securities and Agency Bonds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	2,838		12,363
Available-for-sale securities, Gross Unrealized Gains	0		10
Available-for-sale securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Estimated Fair Value	2,838		12,373
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	10,599		15,567
Available-for-sale securities, Gross Unrealized Gains	30		63
Available-for-sale securities, Gross Unrealized Losses	2		2
Available-for-sale Securities, Estimated Fair Value	10,627		15,628
Mortgage Backed and Asset Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,793	[1]	3,655	[1]
Available-for-sale securities, Gross Unrealized Gains	297	[1]	355	[1]
Available-for-sale securities, Gross Unrealized Losses	16	[1]	7	[1]
Available-for-sale Securities, Estimated Fair Value	2,074	[1]	4,003	[1]
Closed-end bond funds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	14,373		21,914
Available-for-sale securities, Gross Unrealized Gains	2,392		5,340
Available-for-sale securities, Gross Unrealized Losses	402		39
Available-for-sale Securities, Estimated Fair Value	16,363		27,215
Preferred Stock
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	2,406		4,878
Available-for-sale securities, Gross Unrealized Gains	736		2,314
Available-for-sale securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Estimated Fair Value	$ 3,142		$ 7,192

[1] At March 31, 2014 and 2013, approximately $1.1 million and $1.4 million of the estimated fair value presented were mortgage-backed securities, respectively.