Fair Value of Financial Assets and Liabilities - Changes in Level 3 Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Level 3 [Member] - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accounts Payable Accrued and Other Liabilities [Member] | Contingent Consideration [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Opening Balance, Liabilities		$ 53,164	$ 68,838	$ 67,172	$ 65,838
Total realized and unrealized gains (losses) included in Net income (loss), Liabilities	[1]	(966)	(1,965)	(2,009)	(5,952)
Unrealized gains (losses) included in Other comprehensive income (loss), Liabilities		291	(881)	845	(2,040)
Purchases/ Issuances, Liabilities		7,482	1,262	8,191	9,624
Sales/ Settlements, Liabilities		(245)	(1,702)	(15,451)	(12,210)
Closing Balance, Liabilities		61,076	71,244	61,076	71,244
Unrealized gains (losses) for Level 3 Liabilities Outstanding		(675)	(2,846)	(1,164)	(7,992)
Rate Lock Commitments And Forwards, Net [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Opening Balance, Assets		16,304	10,566	3,629	10,254
Total realized and unrealized gains (losses) included in Net income (loss), Assets	[1]	14,608	10,070	14,608	10,070
Sales/ Settlements, Assets		(16,304)	(10,566)	(3,629)	(10,254)
Closing Balance, Assets		14,608	10,070	14,608	10,070
Unrealized gains (losses) for Level 3 Assets Outstanding		$ 14,608	$ 10,070	$ 14,608	$ 10,070

[1] Realized and unrealized gains (losses) are reported in “Other expenses” and “Other income (loss),” as applicable, in the Company’s unaudited condensed consolidated statements of operations.