Share-based Compensation Plans and Awards - Warrants (Details) (USD $)
In Thousands, except Per Share data, unless otherwise specified
1 Months Ended 9 Months Ended
Jan. 31, 2011
Jan. 31, 2011
LAF Warrant [Member]
Jan. 31, 2008
LAF Warrant [Member]
Sep. 30, 2012
BEI Warrant [Member]
Class of Warrant or Right [Line Items]        
Fully-vested warrant exercisable period       4 years
Warrants to purchase common stock (in shares)     312 375
Warrants exercise price (usd per share)     $ 12.00 $ 12.00
Warrants exercised into common stock (in shares) 477 184