Acquisitions (Detail) - Acquisition Activity - USD ($) $ / shares in Units, $ in Thousands	Dec. 03, 2015	Dec. 02, 2014	Aug. 08, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assets
Goodwill				$ 319,007	$ 310,589	$ 264,062	$ 265,477
Liabilities
Intangible liabilities				$ 9,034
Peoples
Assets
Cash and due from banks and interest-bearing deposits in other banks	$ 781
Securities available-for-sale	41,492
FHLB and FRB stock	558
Loans	53,917
OREO	515
Investment in BOLI	0
Goodwill	7,544
Other intangible assets	580
Premises, furniture, and equipment	2,215
Accrued interest receivable and other assets	2,911
Total assets	110,513
Liabilities
Noninterest-bearing deposits	15,869
Interest-bearing deposits	75,944
Total deposits	91,813
Intangible liabilities	0
Borrowed funds	1,200
Senior and subordinated debt	0
Accrued interest payable and other liabilities	672
Total liabilities	93,685
Consideration Paid
Common stock (2014 - 2,440,754 shares issued at $15.737 per share), net of $110,000 in issuance costs	0
Cash paid	16,828
Total consideration paid	$ 16,828
Popular
Assets
Cash and due from banks and interest-bearing deposits in other banks			$ 161,276
Securities available-for-sale			0
FHLB and FRB stock			0
Loans			549,386
OREO			0
Investment in BOLI			0
Goodwill			32,181
Other intangible assets			8,003
Premises, furniture, and equipment			4,647
Accrued interest receivable and other assets			6,574
Total assets			762,067
Liabilities
Noninterest-bearing deposits			163,299
Interest-bearing deposits			568,573
Total deposits			731,872
Intangible liabilities			10,631		$ 10,600
Borrowed funds			0
Senior and subordinated debt			0
Accrued interest payable and other liabilities			564
Total liabilities			743,067
Consideration Paid
Common stock (2014 - 2,440,754 shares issued at $15.737 per share), net of $110,000 in issuance costs			0
Cash paid			19,000
Total consideration paid			$ 19,000
Great Lakes
Assets
Cash and due from banks and interest-bearing deposits in other banks		$ 78,609
Securities available-for-sale		219,279
FHLB and FRB stock		1,970
Loans		223,169
OREO		1,244
Investment in BOLI		10,373
Goodwill		10,339
Other intangible assets		6,192
Premises, furniture, and equipment		5,011
Accrued interest receivable and other assets		10,059
Total assets		566,245
Liabilities
Noninterest-bearing deposits		110,885
Interest-bearing deposits		353,424
Total deposits		464,309
Intangible liabilities		0
Borrowed funds		29,490
Senior and subordinated debt		9,809
Accrued interest payable and other liabilities		6,887
Total liabilities		510,495
Consideration Paid
Common stock (2014 - 2,440,754 shares issued at $15.737 per share), net of $110,000 in issuance costs		38,300
Cash paid		17,450
Total consideration paid		$ 55,750
Common stock, shares issued		2,440,754
Shares issued (dollars per share)		$ 15.737
Issuance costs		$ 110