Income Taxes - Schedule of Net Operating Loss Carryforwards (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 425,973
2019
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	8,397
2020 to 2022
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	224,550
2023 to 2025
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	40,434
2026 to 2028
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	14,528
Thereafter
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	138,064
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	249,138
Net operating loss carryforwards that will not be available to offset	241,800
Federal | 2019
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	0
Federal | 2020 to 2022
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	210,114
Federal | 2023 to 2025
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	26,838
Federal | 2026 to 2028
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	12,186
Federal | Thereafter
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	0
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	776
State | 2019
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	0
State | 2020 to 2022
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	0
State | 2023 to 2025
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	0
State | 2026 to 2028
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	45
State | Thereafter
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	731
Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	176,059
Foreign | 2019
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	8,397
Foreign | 2020 to 2022
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	14,436
Foreign | 2023 to 2025
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	13,596
Foreign | 2026 to 2028
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	2,297
Foreign | Thereafter
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 137,333