Fair Value - Fair Value Measurement (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assumed Gain/(Loss) From Loan Sale	$ 6,586
Interest Rate Movement Effect	6,080
Servicing Rights Value	8,133
Security Price Change	(5,216)
Total Fair Value Measurement Gain/(Loss)	15,583	$ 14,111
Senior Notes due 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior notes	598,925	598,301
Senior Notes Due Two Thousand Thirty [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior notes	918,470	0
Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior notes	1,517,395	598,301
Level 2 | Fair Value, Measurements, Recurring | Senior Notes due 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes fair value	630,000	626,520
Level 2 | Fair Value, Measurements, Recurring | Senior Notes Due Two Thousand Thirty [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes fair value	982,620	0
Level 2 | Fair Value, Measurements, Recurring | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes fair value	1,612,620	626,520
Home Building
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior notes	1,517,395	598,301
Mortgage Banking | Level 2 | Fair Value, Measurements, Recurring | Rate lock commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assumed Gain/(Loss) From Loan Sale	3,227
Interest Rate Movement Effect	3,263
Servicing Rights Value	4,267
Security Price Change	0
Total Fair Value Measurement Gain/(Loss)	10,757
Derivative, Notional Amount	617,308
Mortgage Banking | Level 2 | Fair Value, Measurements, Recurring | Forward sales contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assumed Gain/(Loss) From Loan Sale	0
Interest Rate Movement Effect	0
Servicing Rights Value	0
Security Price Change	(5,216)
Total Fair Value Measurement Gain/(Loss)	(5,216)
Derivative, Notional Amount	916,588
Mortgage Banking | Level 2 | Fair Value, Measurements, Recurring | Mortgages held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assumed Gain/(Loss) From Loan Sale	3,359
Interest Rate Movement Effect	2,817
Servicing Rights Value	3,866
Security Price Change	0
Total Fair Value Measurement Gain/(Loss)	10,042	7,019
Derivative, Notional Amount	$ 439,718	$ 485,106