Long-Term Debt and Short-Term Borrowings - Schedule of Long-Term Debt and Short-Term Borrowings (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total long-term debt	$ 2,022,598	$ 2,574,301
Less: current maturities of long-term debt	(8)	(11)
Less: unamortized debt issuance costs	(22,987)	(26,164)
Total long-term debt, net of current maturities	1,999,603	2,548,126
Warehouse lines of credit (which fund loans that U.S. Government Sponsored Enterprises have committed to purchase)	910,766	1,254,653
Other	16	16
Total short-term borrowings	910,782	1,254,669
Warehouse Agreement Borrowings [Member]
Debt Instrument [Line Items]
Warehouse lines of credit (which fund loans that U.S. Government Sponsored Enterprises have committed to purchase)	910,766	1,254,653
Senior secured term loans [Member]
Debt Instrument [Line Items]
Total long-term debt	200,000	751,875
Other Long Term Debt [Member]
Debt Instrument [Line Items]
Total long-term debt	8	14
5.00% Senior Notes [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Total long-term debt	800,000	800,000
4.875% Senior Notes [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Total long-term debt	596,273	595,912
5.25% Senior Notes [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Total long-term debt	426,317	426,500
Pricing at daily one-month LIBOR plus 1.45%, maturing February 28, 2017 [Member] \| Warehouse Agreement Borrowings [Member]
Debt Instrument [Line Items]
Warehouse lines of credit (which fund loans that U.S. Government Sponsored Enterprises have committed to purchase)	$ 910,766	$ 1,254,653

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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