Fair Value of Financial Assets and Liabilities - Quantitative Information about Level 3 Fair Value Measurements (Detail) $ in Thousands	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingency consideration liability	$ 33,337	$ 45,172
Derivative contract, Assets	106,656	72,926
Derivative contract, Liabilities	$ 77,909	25,661
Weighted Average | Probability of meeting earnout and contingencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input	0.921
Nasdaq Forwards
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, Assets	$ 47,675	26,502
Forward Sale Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, Assets	229	14,389
Derivative contract, Liabilities	77,909	13,537
Rate lock commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, Assets	58,752	32,035
Derivative contract, Liabilities		12,124
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingency consideration liability	$ 33,337	$ 45,172
Level 3 | Minimum | Discount rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input	0.003	0.003
Level 3 | Minimum | Probability of meeting earnout and contingencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input	0.90	0.90
Level 3 | Maximum | Discount rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input	0.104	0.104
Level 3 | Maximum | Probability of meeting earnout and contingencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input	1	1
Level 3 | Weighted Average | Discount rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input	0.075	0.086
Level 3 | Weighted Average | Probability of meeting earnout and contingencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input		0.981
Level 3 | Nasdaq Forwards
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, Assets	$ 47,675	$ 26,502
Level 3 | Nasdaq Forwards | Minimum | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derviatve asset, measurement input	0.256	0.257
Level 3 | Nasdaq Forwards | Maximum | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derviatve asset, measurement input	0.3483	0.348
Level 3 | Nasdaq Forwards | Weighted Average | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input		0.322
Derviatve asset, measurement input	0.398
Level 3 | Forward Sale Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, Assets	$ 229	$ 14,389
Derivative contract, Liabilities	77,909	13,537
Level 3 | Rate lock commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, Assets	58,752	32,035
Derivative contract, Liabilities	$ 0	$ 12,124