Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity (Repurchase Program and Warrants) (Details)

v3.6.0.2
Shareholders' Equity (Repurchase Program and Warrants) (Details) - USD ($)
 12 Months Ended 118 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2016
Nov. 07, 2016
Nov. 30, 2014
Oct. 31, 2011
Mar. 31, 2007
Class of Stock [Line Items]                
Shares authorized for additional repurchase (in shares)         10,000,000      
Remaining authorized repurchase amount $ 10,000,000     $ 10,000,000        
Warrant exercise 13,236,333 646,000 13,333          
Exercise of warrants (in shares) 12,389,544              
Exercise of stock options, shares tendered in payment of exercise price (in shares)   196,518            
Intrinsic value of warrant exercised $ 9,320,000 $ 966,000 $ 23,000          
Warrant                
Class of Stock [Line Items]                
Exercise of stock options, shares tendered in payment of exercise price (in shares) 846,789 196,518            
Common Stock                
Class of Stock [Line Items]                
Shares authorized for repurchase (in shares)               2,500,000
Shares authorized for additional repurchase (in shares)           10,000,000 5,000,000  
Shares repurchased (in shares) 5,230,433 5,673,415   17,500,000        
Shares repurchased, value $ 12,711,000 $ 16,355,000   $ 44,690,000        
Exercise of warrants (in shares) 12,389,544 449,482 13,333