MERGERS AND ACQUISITIONS - Additional Information (Detail) $ / shares in Units, $ in Thousands				3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 11, 2017 USD ($) $ / shares shares	Apr. 22, 2016 USD ($) Branch	Feb. 13, 2016 USD ($) shares	Sep. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Goodwill recorded as a result of merger				$ 2,254,831		$ 2,254,831		$ 1,032,129
Merger-related expenses				$ 1,381	$ 299	$ 55,459	$ 35,790
Warrant Expires in 2019 [Member]
Business Acquisition [Line Items]
Warrant issued, exercise price (in dollars per share) | $ / shares				$ 11.52		$ 11.52
Yadkin Financial Corporation (YDKN) [Member]
Business Acquisition [Line Items]
Assets acquired as a result of merger	$ 6,781,270
Loans acquired as a result of merger	5,114,355
Deposits acquired as a result of merger	5,176,915
Value of acquisition	$ 1,784,783
Closing price of common stock (in dollars per share) | $ / shares	$ 15.97
Number of shares | shares	111,619,622
Common shares to be acquired, shares | shares	51,677,565
Ratio of shares entitled to receive as per merger agreement	2.16
Goodwill recorded as a result of merger	$ 1,222,567
Core deposit intangibles recorded as result of the acquisition	55,700
Estimated useful life of intangibles, years						10 years
Merger-related expenses						$ 55,100
Percentage of contract termination cost				31.30%		31.30%
Issuance costs incurred in connection with acquisition				$ 600		$ 600
Cash acquired as a result of merger	$ 196,964
Yadkin Financial Corporation (YDKN) [Member] | Merger - Related Expenses [Member]
Business Acquisition [Line Items]
Percentage of severance costs				25.00%		25.00%
Yadkin Financial Corporation (YDKN) [Member] | Warrant Expires in 2019 [Member]
Business Acquisition [Line Items]
Warrant issued (in shares) | shares	207,320			209,232		209,232
Warrant issued, exercise price (in dollars per share) | $ / shares	$ 9.63			$ 9.54		$ 9.54
Fifth Third Bank Branches [Member]
Business Acquisition [Line Items]
Assets acquired as a result of merger		$ 312,424
Loans acquired as a result of merger		95,354
Deposits acquired as a result of merger		302,529
Value of acquisition		0
Goodwill recorded as a result of merger		14,146
Core deposit intangibles recorded as result of the acquisition		$ 4,100
Number of branch-banking locations acquired | Branch		17
Cash acquired as a result of merger		$ 198,872
Fixed and other assets acquired as a result of merger		$ 14,100
Percentage of deposit premium paid		1.97%
Metro Bancorp Inc [Member]
Business Acquisition [Line Items]
Assets acquired as a result of merger			$ 2,783,665
Loans acquired as a result of merger			1,862,447
Deposits acquired as a result of merger			2,328,238
Value of acquisition			$ 404,242
Number of shares | shares			34,041,181
Goodwill recorded as a result of merger			$ 185,054
Core deposit intangibles recorded as result of the acquisition			24,200
Merger-related expenses						$ 400		$ 31,000
Issuance costs incurred in connection with acquisition				$ 700		$ 700
Cash acquired as a result of merger			$ 46,890
Common shares acquired, shares | shares			14,345,319
Metro Bancorp Inc [Member] | Merger - Related Expenses [Member]
Business Acquisition [Line Items]
Percentage of severance costs				39.90%		39.90%