XML 32 R20.htm IDEA: XBRL DOCUMENT v3.7.0.1
Fair Value of Financial Instruments (Available-for-sale securities) (Details) - USD ($)
$ in Thousands
Jun. 30, 2017
Dec. 31, 2016
Fair Value of Financial Instruments [Abstract]    
Amortized cost $ 395,055 $ 455,109
Unrealized gains (losses) on available-for-sale securities (589) (218)
Fair market value $ 394,466 $ 454,891