Stockholders' Equity (Narrative) (Details)		12 Months Ended
	Dec. 31, 2013 USD ($)	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) employee $ / shares shares	Oct. 31, 2011 USD ($)	Dec. 19, 2006 $ / shares	Dec. 18, 2006 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expenses recognized		$ 4,441,000	$ 3,465,000	$ 4,007,000
Share-based compensation, income tax benefit		0
Share repurchase program, amount authorized		$ 80,500,000			$ 80,500,000
Share repurchase program, expiration date		Dec. 31, 2015
Stock repurchased and retired, shares | shares		1,526,306	3,822,434	2,404,034
Stock repurchased and retired, value		$ 12,811,000	$ 24,400,000	$ 12,519,000
Stock repurchased, value		$ 78,100,000
Dividend distribution declared, number of preferred stock purchase right per outstanding share of common stock | shares							1
Number of common stock entitled to purchase per preferred stock purchase right | shares							0.001
Preferred stock par value | $ / shares		$ 0.001	$ 0.001
Agreement, period of required evaluation		3 years
Series D Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock par value | $ / shares						$ 0.001
Preferred stock redemption price per share | $ / shares						$ 25.00
Minimum percentage of company common stock being acquired for the rights to become exercisable						15.00%
Common stock purchase discount percentage in the even of certain business combinations						50.00%
Redemmed price per share authorized by the board prior to a group or person acquiring 15% of common stock | $ / shares						$ 0.001
Two Company Board Members [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees affected by plan modification | employee				2
Share based compensation costs				$ 200,000
Two Former Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration	1 year			90 days
Number of employees affected by plan modification | employee				2
Share based compensation costs				$ 100,000
Equity Incentive Plan [Member] | 2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized under plan | shares		6,550,000
Award expiration		10 years
Vesting period		4 years
Equity Incentive Plan [Member] | 2005 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized under plan | shares		13,600,000
Award expiration		10 years
Vesting period		4 years
Shares reserved for future issuance | shares		0
Equity Incentive Plan [Member] | 2004 Director Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized under plan | shares		1,765,000
Award expiration		10 years
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 months
Shares reserved for future issuance | shares		1,300,000
Shares available for issuance | shares		432,795
Award expiration date		Jul. 25, 2016
Stock plan maximum percentage withheld by employee		15.00%
Common stock shares that can be purchased | shares		1,000
Offering period		3 months
Stock discount percentage		85.00%
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value of options per share | $ / shares		$ 4.18	$ 2.43	$ 2.56
Intrinsic value of options at exercise	$ 1,300,000	$ 4,700,000	$ 2,400,000	$ 1,300,000
Estimated fair value of shares vested		3,900,000	3,200,000	3,800,000
Unrecognized compensation expense, net of forfeitures		$ 5,500,000
Compensation expense weighted average period recognized		2 years 5 months 12 days
Cash from stock option exercise		$ 4,600,000	5,500,000	1,600,000
Performance-Based Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation costs		$ 20,000	100,000	39,000
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of options at exercise
RSUs [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		1 year
Vesting percentage		25.00%
RSUs [Member] | Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 years
PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration		10 years
Share based compensation costs		$ 100,000	$ 0	$ 0
RSUs and PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value of options per share | $ / shares		$ 8.95	$ 4.52	$ 4.98
Unrecognized compensation expense, net of forfeitures		$ 2,500,000
Unrecognized compensation expense, weighted-average remaining period for recognition, in years		2 years 1 month 6 days
Maximum [Member] | Two Company Board Members [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration	2 years			90 days
Maximum [Member] | Equity Incentive Plan [Member] | 2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of addtional shares | shares		3,000,000
Inventory [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expenses recognized		$ 100,000	$ 100,000	$ 100,000