Stock-Based Compensation (Details) (Stock option, USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Stock option
Summary of stock option activity - Shares
Options outstanding at the beginning of the period (in shares)	3,899
Granted (in shares)	0
Exercised (in shares)	0
Cancelled (in shares)	0
Options outstanding at the end of the period (in shares)	3,899
Options exercisable at the end of the period (in shares)	1,884
Options vested and expected to vest at the end of the period (in shares)	3,741
Summary of stock option activity - Weighted-Average Exercise Price (in dollars per share)
Options outstanding at the beginning of the period (in dollars per share)	$ 3.10
Granted (in dollars per share)	$ 0.00
Exercised (in dollars per share)	$ 0.00
Cancelled (in dollars per share)	$ 0.00
Options outstanding at the end of the period (in dollars per share)	$ 3.10
Options exercisable at the end of the period (in dollars per share)	$ 2.46
Options vested and expected to vest at the end of the period (in dollars per share)	$ 3.07
Weighted-Average Contractual Life (In Years)
Options outstanding at the end of the period	7 years 9 months 25 days
Options exercisable at the end of the period	6 years 10 months 24 days
Options vested and expected to vest at the end of the period	7 years 9 months 11 days
Aggregate Intrinsic Value
Options outstanding at the end of the period (in dollars)	$ 1,340,000
Options exercisable at the end of the period (in dollars)	1,262,000
Options vested and expected to vest at the end of the period (in dollars)	1,337,000
Additional disclosures
Total grant date fair value of stock options vested	$ 500,000