Fair Value of Financial Assets and Liabilities - Quantitative Information about Level 3 Fair Value Measurements (Detail) $ in Thousands	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingency consideration liability	$ 45,172	$ 32,551
Derivative contract, Assets	72,926	92,528
Derivative contract, Liabilities	$ 25,661	16,678
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
Nasdaq Forwards
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, Assets	$ 26,502	77,619
Forward Sale Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, Assets	14,389	8,177
Derivative contract, Liabilities	13,537	9,208
Rate lock commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, Assets	32,035	6,732
Derivative contract, Liabilities	12,124	7,470
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingency consideration liability	$ 45,172	$ 32,551
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	0.99
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	0.086	0.082
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		0.996
Level 3 | Nasdaq Forwards
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, Assets	$ 26,502	$ 77,619
Level 3 | Nasdaq Forwards | Minimum | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derviatve asset, measurement input	0.257	0.237
Level 3 | Nasdaq Forwards | Maximum | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derviatve asset, measurement input	0.348	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		0.302
Derviatve asset, measurement input	0.322
Level 3 | Forward Sale Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, Assets	$ 14,389	$ 8,177
Derivative contract, Liabilities	13,537	9,208
Level 3 | Rate lock commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, Assets	32,035	6,732
Derivative contract, Liabilities	$ 12,124	$ 7,470