v3.2.0.727
Investment Securities - Continuous Unrealized Loss (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2015
Jun. 30, 2014
Jun. 30, 2015
Jun. 30, 2014
Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]          
Fair value, less than 12 months $ 120,897   $ 120,897   $ 73,165
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss Accumulated In Investments (526)   (526)   (239)
Fair value, 12 months or more 0   0   1,562
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss, Accumulated in Investments 0   0   (35)
Total fair value 120,897   120,897   74,727
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss, Accumulated in Investments (526)   (526)   (274)
Other than temporary impairment losses 0 $ 0 0 $ 0  
Corporate Bonds          
Schedule of Available-for-sale Securities [Line Items]          
Fair value, less than 12 months 29,312   29,312   33,348
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss Accumulated In Investments (34)   (34)   (48)
Fair value, 12 months or more 0   0   0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss, Accumulated in Investments 0   0   0
Total fair value 29,312   29,312   33,348
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss, Accumulated in Investments (34)   (34)   (48)
Commercial Paper          
Schedule of Available-for-sale Securities [Line Items]          
Fair value, less than 12 months 8,926   8,926    
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss Accumulated In Investments (3)   (3)    
Fair value, 12 months or more 0   0    
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss, Accumulated in Investments 0   0    
Total fair value 8,926   8,926    
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss, Accumulated in Investments (3)   (3)    
US Treasury Notes          
Schedule of Available-for-sale Securities [Line Items]          
Fair value, less than 12 months 8,191   8,191   6,068
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss Accumulated In Investments (1)   (1)   (16)
Fair value, 12 months or more         0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss, Accumulated in Investments         0
Total fair value 8,191   8,191   6,068
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss, Accumulated in Investments (1)   (1)   (16)
Mortgage-backed Securities          
Schedule of Available-for-sale Securities [Line Items]          
Fair value, less than 12 months 64,444   64,444   21,495
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss Accumulated In Investments (477)   (477)   (163)
Fair value, 12 months or more 0   0   1,143
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss, Accumulated in Investments 0   0   (14)
Total fair value 64,444   64,444   22,638
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss, Accumulated in Investments (477)   (477)   (177)
Municipal Bonds          
Schedule of Available-for-sale Securities [Line Items]          
Fair value, less than 12 months 393   393   0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss Accumulated In Investments (7)   (7)   0
Fair value, 12 months or more 0   0   419
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss, Accumulated in Investments 0   0   (21)
Total fair value 393   393   419
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss, Accumulated in Investments (7)   (7)   (21)
Asset-backed Securities          
Schedule of Available-for-sale Securities [Line Items]          
Fair value, less than 12 months 9,631   9,631   12,254
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss Accumulated In Investments (4)   (4)   (12)
Fair value, 12 months or more 0   0   0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss, Accumulated in Investments 0   0   0
Total fair value 9,631   9,631   12,254
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss, Accumulated in Investments $ (4)   $ (4)   $ (12)