Consolidated Statements of Stockholders' Equity (Parenthetical)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Exercise of stock options 563 348 184
Employee stock purchase plan sales, shares 89 110 94
Sale of common stock, shares 7,547 4,774 437
Purchases of treasury stock, shares     12
Common Stock [Member]
      
Exercise of stock options 563 348 184
Employee stock purchase plan sales, shares 89 110 94
Sale of common stock, shares 7,547 4,774 437
Additional Paid-In Capital [Member]
      
Exercise of stock options 563 348 184
Employee stock purchase plan sales, shares 89 110 94
Sale of common stock, shares 7,547 4,774 437
Purchases of treasury stock, shares     12