Fair Value Information - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps, assets	$ 5,783	$ 9,344
Interest rate swaps, liabilities	608,811	700,048
Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps, assets	0	0
Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps, assets	5,783	9,344
Interest rate swaps, liabilities	5,783	9,344
Fair Value on Recurring Basis [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Total liabilities	0	0
Fair Value on Recurring Basis [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,276,249	2,377,990
Total liabilities	5,783	9,344
Fair Value on Recurring Basis [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Total liabilities	0	0
Fair Value on Recurring Basis [Member] | Municipal Bonds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	0	0
Fair Value on Recurring Basis [Member] | Municipal Bonds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	80,071	160,973
Fair Value on Recurring Basis [Member] | Municipal Bonds [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	0	0
Fair Value on Recurring Basis [Member] | Government Agency/GSE [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	0	0
Fair Value on Recurring Basis [Member] | Government Agency/GSE [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	2,752	5,745
Fair Value on Recurring Basis [Member] | Government Agency/GSE [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	0	0
Fair Value on Recurring Basis [Member] | Residential Mortgage-backed Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	0	0
Fair Value on Recurring Basis [Member] | Residential Mortgage-backed Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	1,834,748	1,813,097
Fair Value on Recurring Basis [Member] | Residential Mortgage-backed Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	0	0
Fair Value on Recurring Basis [Member] | CMO/REMIC - Residential [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	0	0
Fair Value on Recurring Basis [Member] | CMO/REMIC - Residential [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	347,189	383,781
Fair Value on Recurring Basis [Member] | CMO/REMIC - Residential [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	0	0
Fair Value on Recurring Basis [Member] | Other Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	0	0
Fair Value on Recurring Basis [Member] | Other Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	5,706	5,050
Fair Value on Recurring Basis [Member] | Other Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	0	0
Fair Value on Recurring Basis [Member] | Investment Securities - AFS [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	0	0
Fair Value on Recurring Basis [Member] | Investment Securities - AFS [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	2,270,466	2,368,646
Fair Value on Recurring Basis [Member] | Investment Securities - AFS [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	0	0
Fair Value on Recurring Basis [Member] | Interest Rate Swaps [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps, assets	0	0
Interest rate swaps, liabilities	0	0
Fair Value on Recurring Basis [Member] | Interest Rate Swaps [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps, assets	5,783	9,344
Interest rate swaps, liabilities	5,783	9,344
Fair Value on Recurring Basis [Member] | Interest Rate Swaps [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps, assets	0	0
Interest rate swaps, liabilities	0	0
Fair Value on Recurring Basis [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,276,249	2,377,990
Total liabilities	5,783	9,344
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	80,071	160,973
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | Government Agency/GSE [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	2,752	5,745
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | Residential Mortgage-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	1,834,748	1,813,097
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | CMO/REMIC - Residential [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	347,189	383,781
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | Other Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	5,706	5,050
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | Investment Securities - AFS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - AFS	2,270,466	2,368,646
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps, assets	5,783	9,344
Interest rate swaps, liabilities	$ 5,783	$ 9,344