Schedule I - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows From Operating Activities:
Net (loss) income	$ (312,321)	$ 89,476	$ 44,788
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Equity in net loss (income) of subsidiary	312,321	(89,476)	(44,788)
Net cash (used in) provided by operating activities	(120,729)	348,416	293,935
Cash Flows From Investing Activities:
Net cash used in investing activities	(109,175)	(195,193)	(180,029)
Cash Flows From Financing Activities:
Exercise of stock options	2,920	3,795	4,282
Net cash provided by (used in) financing activities	624,204	(147,305)	(112,896)
Change in Cash and Cash Equivalents, including Restricted Cash	394,300	5,918	1,010
Cash and Cash Equivalents, including Restricted Cash—Beginning of year	40,925	35,007	33,997
Cash and Cash Equivalents, including Restricted Cash—End of year	435,225	40,925	35,007
Parent Company [Member]
Cash Flows From Operating Activities:
Net (loss) income	(312,321)	89,476	44,788
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Equity in net loss (income) of subsidiary	312,321	(89,476)	(44,788)
Cash Flows From Investing Activities:
Dividends (forfeited) received from subsidiary- return of capital, net of forfeitures	(1)	(5)	(61)
Capital contributed to subsidiary from exercises of stock options	(2,621)	(3,696)	(4,230)
Net cash used in investing activities	(2,622)	(3,701)	(4,291)
Cash Flows From Financing Activities:
Exercise of stock options	2,920	3,795	4,282
Dividends paid to common stockholders	(12)	(61)	(325)
Net cash provided by (used in) financing activities	2,908	3,734	3,957
Change in Cash and Cash Equivalents, including Restricted Cash	286	33	(334)
Cash and Cash Equivalents, including Restricted Cash—Beginning of year	169	136	470
Cash and Cash Equivalents, including Restricted Cash—End of year	455	169	136
Supplemental Disclosures of Noncash Financing Activities
Dividends from subsidiary- return of capital, for purchase of treasury stock	12,406	150,000	98,032
Parent Company [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Cash Flows From Operating Activities:
Net (loss) income	(312,321)	89,476	44,788
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Equity in net loss (income) of subsidiary	$ 312,321	$ (89,476)	$ (44,788)