REGULATORY MATTERS, COMMITMENTS AND CONTINGENCIES - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Jul. 31, 2013	Feb. 16, 2011	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Cash dividends declared on preferred stock			$ 2,676	$ 223	$ 0
Proceeds from sale of available-for-sale securities			$ 23,408	$ 219,780	$ 0
Loans acquired on exchange of loan held for sale		$ 136,100
Common Equity Tier 1 Capital Conservation Buffer First Year			0.625%
Banking Organizations Basel Advanced Approach Asset Requirement			$ 250,000,000
Foreign Subsidiaries Basel Advanced Approach Asset Requirement			$ 10,000,000
Basel III [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital Conservation Buffer	2.50%
Common Equity Tier 1 Capital To Risk Weight Assets Ratio	4.50%
Common equity tier 1 capital to risk weight assets ratio plus common equity tier1 capital conservation buffer	7.00%
Total Tier 1 Capital To Risk Weight Assets Ratio	6.00%
Total Tier 1 Capital To Risk Weight Assets Ratio Plus Common Equity Tier 1 Capital Conservation Buffer	8.50%
Total Tier 1 Capital And Tier 2 Capital To Risk Weight Assets Ratio Plus Common Equity Tier 1 Capital Conservation Buffer	10.50%
Leverage Ratio	4.00%
Total Tier1 Capital And Tier 2 Capital To Risk Weight Assets Ratio	8.00%
Cpg Gs [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Cash realized on sale of loan		$ 88,500