Income Taxes (Reconciliation of Taxes Provided to Federal Statutory Rate) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended									12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012		Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Income Taxes Reconciliation Of Taxes Provided To Federal Statutory Rate Details
Tax provision at statutory rate										$ 8,048	$ 2,337	$ 2,226
State income taxes before valuation allowance, net of federal effect										846	408	372
Research and development credits										(385)	(211)	(128)
Change in valuation allowance										1,038	(65,042)	(2,147)
Loss from change in fair value of warrant liability												(57)
Compensation/option differences										(207)	(87)	(291)
Non-deductible compensation										403	220	75
Other										(10)	21	5
Income tax expense (benefit)	$ 2,007	$ 913	$ 1,032	$ 5,781	$ (62,070)	[1]	$ 15	$ 22	$ (321)	$ 9,733	$ (62,354)	$ 55

[1] Comparability affected by income tax benefit of $62.1 million recorded in the fourth quarter of 2012 related to the release of deferred tax asset valuation allowance.