Description of Business and Summary of Significant Accounting Policies (Computation of basic and diluted net income (loss) per share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of computation of basic and diluted net income (loss) per share
Net income (loss)	$ 2,867	[1]	$ 5,228	[2]	$ 31	[3]	$ (952)	[4]	$ 515	[5]	$ 569	[6]	$ (200)	[7]	$ (2,322)	[8]	$ 7,174	$ (1,438)	$ (6,056)
Effect of assumed conversion of convertible debentures
Weighted average common shares outstanding			28,736		28,672		28,122		27,851		27,733		27,669		27,285		28,568	27,637	26,234
Convertible debentures																	0	0	0
Weighted average common shares outstanding, assuming dilution			28,748		28,780		28,122		28,285		28,161		27,669		27,285		28,709	27,637	26,234
Net income (loss) per share:
Basic (in dollars per share)			$ 0.18		$ 0.00		$ (0.03)		$ 0.02		$ 0.02		$ (0.01)		$ (0.09)		$ 0.25	$ (0.05)	$ (0.23)
Diluted (in dollars per share)			$ 0.18		$ 0.00		$ (0.03)		$ 0.02		$ 0.02		$ (0.01)		$ (0.09)		$ 0.25	$ (0.05)	$ (0.23)
Options to purchase common stock [Member]
Effect of assumed conversion of convertible debentures
Effect of potentially dilutive securities																	115	0	0
Restricted Stock Awards [Member]
Effect of assumed conversion of convertible debentures
Effect of potentially dilutive securities																	10	0	0
Restricted stock unit awards [Member]
Effect of assumed conversion of convertible debentures
Effect of potentially dilutive securities																	2	0	0
Employee Stock Purchase Plan [Member]
Effect of assumed conversion of convertible debentures
Effect of potentially dilutive securities																	14	0	0

[1] Includes a non-cash expense for stock-based compensation of $527,000.

[2] Includes a non-cash expense for stock-based compensation of $505,000.

[3] Includes a non-cash expense for stock-based compensation of $770,000.

[4] Includes a non-cash expense for stock-based compensation of $1.3 million.

[5] Includes a non-cash expense for stock-based compensation of $142,000.

[6] Includes a non-cash expense for stock-based compensation of $734,000.

[7] Includes a non-cash expense for stock-based compensation of $789,000 and a $2.6 million charge for the accrual for anticipated settlement of a legal matter.

[8] Includes a gain on embedded derivatives of $1.1 million and a non-cash expense for stock-based compensation of $917,000.