Fair Value of Financial Assets and Liabilities - Changes in Level 3 Rate Lock Commitments, Forwards and Contingent Consideration Measured at Fair Value on Recurring Basis (Detail) - Level 3 [Member] - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 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		$ 59,242	$ 63,197	$ 67,172	$ 65,838
Total realized and unrealized gains (losses) included in Net income (loss), Liabilities	[1]	(336)	(2,876)	(1,043)	(3,987)
Unrealized gains (losses) included in Other comprehensive income (loss), Liabilities		1,417	(949)	554	(1,159)
Purchases/ Issuances, Liabilities		688	2,173	710	8,363
Sales/ Settlements, Liabilities		(5,685)	(357)	(15,207)	(10,509)
Closing Balance, Liabilities		53,164	68,838	53,164	68,838
Unrealized gains (losses) for Level 3 Liabilities Outstanding		1,081	(3,825)	(489)	(5,146)
Rate Lock Commitments And Forwards, Net [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Opening Balance, Assets		7,036	2,462	3,629	10,254
Total realized and unrealized gains (losses) included in Net income (loss), Assets	[1]	16,304	10,566	16,304	10,566
Sales/ Settlements, Assets		(7,036)	(2,462)	(3,629)	(10,254)
Closing Balance, Assets		16,304	10,566	16,304	10,566
Unrealized gains (losses) for Level 3 Assets Outstanding		$ 16,304	$ 10,566	$ 16,304	$ 10,566

[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.