Acquisitions, CapitalMark & Magna (Details) - USD ($)				3 Months Ended
		Sep. 01, 2015	Jul. 31, 2015	Mar. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Period for merger dates				1 year
Allocation of total consideration paid [Abstract]
Goodwill				$ 431,840,600	$ 432,232,255
CapitalMark Bank & Trust [Member]
Business Acquisition [Line Items]
Fractional shares of common stock (in shares)			0.50
Stock consideration percentage			90.00%
Cash consideration percentage			10.00%
Average closing price for common stock (in dollars per share)			$ 26.78
Valuation in shares (in shares)			3,300,000
Valuation in dollars			$ 19,700,000
Period for average closing price			10 days
Equity consideration [Abstract]
Total equity consideration, Amount			$ 205,955,000
Fair value of stock options assumed			30,430,000
Non-equity consideration [Abstract]
Cash			19,675,000
Total consideration paid			225,630,000
Allocation of total consideration paid [Abstract]
Fair value of net assets assumed including estimated identifiable intangible assets			67,432,000
Goodwill			158,198,000
Assets [Abstract]
Cash and cash equivalents			28,021,000
Investment securities	[1]		150,400,000
Loans, net of allowance for loan losses	[2]		857,515,000
Mortgage loans held for sale	[2]		1,791,000
Other real estate owned			1,728,000
Core deposit intangible	[3]		6,193,000
Other assets			43,818,000
Total Assets			1,089,466,000
Liabilities [Abstract]
Interest-bearing deposits	[4]		759,383,000
Non-interest bearing deposits			193,798,000
Borrowings	[5]		33,102,000
Other liabilities			35,751,000
Total Liabilities			1,022,034,000
Fair value of net assets assumed including estimated identifiable intangible assets			67,432,000
CapitalMark Bank & Trust [Member] | As Acquired [Member]
Allocation of total consideration paid [Abstract]
Fair value of net assets assumed including estimated identifiable intangible assets			78,791,000
Assets [Abstract]
Cash and cash equivalents			28,021,000
Investment securities	[1]		150,799,000
Loans, net of allowance for loan losses	[2]		880,115,000
Mortgage loans held for sale	[2]		1,791,000
Other real estate owned			1,728,000
Core deposit intangible	[3]		0
Other assets			37,252,000
Total Assets			1,099,706,000
Liabilities [Abstract]
Interest-bearing deposits	[4]		758,492,000
Non-interest bearing deposits			193,798,000
Borrowings	[5]		32,874,000
Other liabilities			35,751,000
Total Liabilities			1,020,915,000
Fair value of net assets assumed including estimated identifiable intangible assets			78,791,000
CapitalMark Bank & Trust [Member] | Preliminary Fair Value Adjustments [Member]
Allocation of total consideration paid [Abstract]
Fair value of net assets assumed including estimated identifiable intangible assets			(11,359,000)
Assets [Abstract]
Cash and cash equivalents			0
Investment securities	[1]		(399,000)
Loans, net of allowance for loan losses	[2]		(22,600,000)
Mortgage loans held for sale	[2]		0
Other real estate owned			0
Core deposit intangible	[3]		6,193,000
Other assets			6,566,000
Total Assets			(10,240,000)
Liabilities [Abstract]
Interest-bearing deposits	[4]		891,000
Non-interest bearing deposits			0
Borrowings	[5]		228,000
Other liabilities			0
Total Liabilities			1,119,000
Fair value of net assets assumed including estimated identifiable intangible assets			$ (11,359,000)
CapitalMark Bank & Trust [Member] | Common Stock [Member]
Equity consideration [Abstract]
Total equity consideration, Number of Shares (in shares)			3,306,184
Total equity consideration, Amount			$ 175,525,000
Magna Bank [Member]
Business Acquisition [Line Items]
Fractional shares of common stock (in shares)		0.3369
Stock consideration percentage		75.00%
Cash consideration percentage		25.00%
Business acquisition share price in cash (in dollars per share)		$ 14.32
Unexercised stock options exchanged for cash (in shares)		139,417
Unexercised stock options exchange price less than exercise price (in dollars per share)		$ 14.32
Valuation in shares (in shares)		1,400,000
Valuation in dollars		$ 19,500,000
Period for average closing price		10 days
Equity consideration [Abstract]
Total equity consideration, Amount		$ 63,538,000
Non-equity consideration [Abstract]
Cash		19,453,000
Cash paid to exchange outstanding stock options		847,000
Total consideration paid		83,838,000
Allocation of total consideration paid [Abstract]
Fair value of net assets assumed including estimated identifiable intangible assets		52,371,000
Goodwill		31,467,000
Assets [Abstract]
Cash and cash equivalents		17,832,000
Investment securities	[6]	59,738,000
Loans, net of allowance for loan losses	[7]	442,348,000
Mortgage loans held for sale	[7]	18,886,000
Other real estate owned	[8]	1,610,000
Core deposit intangible	[3]	3,170,000
Other assets	[9]	37,190,000
Total Assets		580,774,000
Liabilities [Abstract]
Interest-bearing deposits	[10]	403,803,000
Non-interest bearing deposits		48,851,000
Borrowings	[11]	47,406,000
Other liabilities		28,343,000
Total Liabilities		528,403,000
Fair value of net assets assumed including estimated identifiable intangible assets		52,371,000
Magna Bank [Member] | As Acquired [Member]
Allocation of total consideration paid [Abstract]
Fair value of net assets assumed including estimated identifiable intangible assets		57,660,000
Assets [Abstract]
Cash and cash equivalents		17,832,000
Investment securities	[6]	60,018,000
Loans, net of allowance for loan losses	[7]	453,108,000
Mortgage loans held for sale	[7]	18,886,000
Other real estate owned	[8]	1,471,000
Core deposit intangible	[3]	0
Other assets	[9]	32,974,000
Total Assets		584,289,000
Liabilities [Abstract]
Interest-bearing deposits	[10]	402,535,000
Non-interest bearing deposits		48,851,000
Borrowings	[11]	46,900,000
Other liabilities		28,343,000
Total Liabilities		526,629,000
Fair value of net assets assumed including estimated identifiable intangible assets		57,660,000
Magna Bank [Member] | Preliminary Fair Value Adjustments [Member]
Allocation of total consideration paid [Abstract]
Fair value of net assets assumed including estimated identifiable intangible assets		(5,289,000)
Assets [Abstract]
Cash and cash equivalents		0
Investment securities	[6]	(280,000)
Loans, net of allowance for loan losses	[7]	(10,760,000)
Mortgage loans held for sale	[7]	0
Other real estate owned	[8]	139,000
Core deposit intangible	[3]	3,170,000
Other assets	[9]	4,216,000
Total Assets		(3,515,000)
Liabilities [Abstract]
Interest-bearing deposits	[10]	1,268,000
Non-interest bearing deposits		0
Borrowings	[11]	506,000
Other liabilities		0
Total Liabilities		1,774,000
Fair value of net assets assumed including estimated identifiable intangible assets		$ (5,289,000)
Magna Bank [Member] | Common Stock [Member]
Equity consideration [Abstract]
Total equity consideration, Number of Shares (in shares)		1,371,717
Total equity consideration, Amount		$ 63,538,000

[1] The amount represents the adjustment of the book value of CapitalMark's investment securities to their estimated fair value on the date of acquisition.

[2] The amount represents the adjustment of the net book value of CapitalMark's loans to their estimated fair value based on current interest rates and expected cash flows, which includes estimates of expected credit losses inherent in the portfolio.

[3] The amount represents the fair value of the core deposit intangible asset created in the acquisition.

[4] The adjustment is necessary because the weighted average interest rate of CapitalMark's deposits exceeded the cost of similar funding at the time of acquisition. The fair value adjustment will be amortized to reduce future interest expense over the life of the portfolio.

[5] The adjustment is necessary because the weighted average interest rate of CapitalMark's FHLB advances exceeded the cost of similar funding at the time of acquisition. The fair value adjustment will be amortized to reduce future interest expense over the life of the portfolio.

[6] The amount represents the adjustment of the book value of Magna's investment securities to their estimated fair value on the date of acquisition.

[7] The amount represents the adjustment of the net book value of Magna's loans to their estimated fair value based on current interest rates and expected cash flows, which includes estimates of expected credit losses inherent in the portfolio.

[8] The amount represents the adjustment to the book value of Magna's OREO to fair value on the date of acquisition.

[9] The amount represents the deferred tax asset recognized on the fair value adjustment of Magna's acquired assets and assumed liabilities as well as the fair value adjustment for property, equipment and other assets.

[10] The adjustment is necessary because the weighted average interest rate of Magna's deposits exceeded the cost of similar funding at the time of acquisition. The fair value adjustment will be amortized to reduce future interest expense over the life of the portfolio.

[11] The adjustment is necessary because the weighted average interest rate of Magna's FHLB advances exceeded the cost of similar funding at the time of acquisition. The fair value adjustment will be amortized to reduce future interest expense over the life of the portfolio.