GOODWILL AND OTHER INTANGIBLE ASSETS - Carrying Amounts of Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Goodwill [Line Items]
Goodwill	$ 339,538,000	$ 152,152,000	$ 152,152,000	$ 26,254,000
Finite-lived Intangible Assets [Roll Forward]
Core Deposit Intangible, Amortization expense	(5,939,000)	(3,098,000)	(2,157,000)
Tax basis in goodwill from mergers and acquisitions	0
Tax deductible goodwill from acquisitions	0
VantageSouth Bancshares, Inc. and Piedmont Community Bank Holdings, Inc.
Goodwill [Line Items]
Goodwill			125,898,000
Core Deposits
Finite-lived Intangible Assets [Roll Forward]
Core Deposit Intangible, Gross, Beginning Balance	20,386,000	20,386,000	7,435,000
Core Deposit Intangible, Gross, Ending Balance	40,276,000	20,386,000	20,386,000
Core Deposit Intangible, Accumulated Amortization, Beginning Balance	(6,807,000)	(3,709,000)	(1,552,000)
Core Deposit Intangible, Amortization expense	(5,940,000)	(3,098,000)	(2,157,000)
Core Deposit Intangible, Accumulated Amortization, Ending Balance	(12,747,000)	(6,807,000)	(3,709,000)
Core Deposit Intangible, Net	$ 27,529,000	$ 13,579,000	16,677,000	$ 5,883,000
Core deposit intangible from the ECB merger, weighted average useful life (in years)	10 years
Core Deposits | VantageSouth Bancshares, Inc. and Piedmont Community Bank Holdings, Inc.
Finite-lived Intangible Assets [Roll Forward]
Core Deposit Intangible Balance from Merger			$ 12,951,000
Core Deposits | NewBridge Bancorp
Finite-lived Intangible Assets [Roll Forward]
Core Deposit Intangible Balance from Merger	$ 19,890,000