Annual report pursuant to Section 13 and 15(d)

Reconciliation of Beginning and Ending Balance for Liabilities Measured at Fair Value on Recurring Basis Unobservable Inputs (Detail)

v3.8.0.1
Reconciliation of Beginning and Ending Balance for Liabilities Measured at Fair Value on Recurring Basis Unobservable Inputs (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Fair Value Disclosures [Abstract]    
Beginning balances - Liabilities $ 0 $ 373
Total loss included in accumulated other comprehensive loss 0 71
Settlements included in interest expense 0 (444)
Ending balances - Liabilities $ 0 $ 0