CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net income	$ 8,521	$ 2,390
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	0	80
Amortization and write-off of debt issuance costs	0	116
Stock-based compensation and employee purchase plan discount	0	(257)
Loss on sales of marketable securities	0	(281)
Amortization of purchase premium on marketable securities	0	536
Gain on disposal of fixed assets	(109)	(219)
Changes in operating assets and liabilities	(208)	388
Net cash provided by operating activities	8,204	2,753
Cash flows from investing activities:
Proceeds from sales of fixed assets	146	235
Proceeds from sales and maturities of marketable securities	0	41,526
Net cash provided by investing activities	146	41,761
Cash flows from financing activities:
Withholding taxes - stock-based compensation	(7)	(106)
Withdrawals/proceeds from employee stock purchase plan	0	(14)
Net cash used in financing activities	(7)	(120)
Net increase in cash and cash equivalents	8,343	44,394
Cash and cash equivalents at beginning of period	6,520	77,348
Cash and cash equivalents at end of period	$ 14,863	$ 121,742