Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Schedule of Reconciliation of Level 3 Investments Available-for-Sale Securities (Detail)

v3.3.0.814
Fair Value Measurements - Schedule of Reconciliation of Level 3 Investments Available-for-Sale Securities (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Sep. 30, 2015
Sep. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Balance, beginning of period     $ 27,273  
Transfers to / purchases of available-for-sale debt securities     21,190 $ 7,753
Balance, end of period $ 28,186   28,186  
Level 3 [Member]        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Balance, beginning of period 28,500 $ 67,600 27,300  
Transfers to / purchases of available-for-sale debt securities 700   21,200 83,500
Payments on available-for-sale debt securities (200)   (8,800)  
Sale of available-for-sale debt securities   (22,900) (10,800) (43,600)
Gains on debt securities transferred to available for sale       5,000
Gains on debt securities recorded in earnings     800  
Losses on debt securities recorded in OCI (800) (1,300) (1,500) (1,500)
Balance, end of period $ 28,200 $ 43,400 $ 28,200 $ 43,400