Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
		Jun. 30, 2017	Dec. 31, 2016
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Valuation allowance	[1]	$ 1,405	$ 1,071
Recurring
Assets, Fair Value Disclosure [Abstract]
U.S. treasury securities		251	250
U.S. government agency securities		61,900	21,769
Mortgage-backed securities		1,539,050	976,626
State and municipal securities		533,602	212,720
Agency-backed securities		190,220	78,580
Corporate notes and other		102,011	8,601
Total investment securities available-for-sale		2,427,034	1,298,546
Other investments		27,850	10,478
Other assets		12,601	13,340
Total assets at fair value		2,467,485	1,322,364
Liabilities at fair value: [Abstract]
Other liabilities		16,190	15,758
Total liabilities at fair value		16,190	15,758
Recurring | Quoted market prices in an active market (Level 1)
Assets, Fair Value Disclosure [Abstract]
U.S. treasury securities		0	0
U.S. government agency securities		0	0
Mortgage-backed securities		0	0
State and municipal securities		0	0
Agency-backed securities		0	0
Corporate notes and other		24,705	0
Total investment securities available-for-sale		24,705	0
Other investments		0	0
Other assets		0	0
Total assets at fair value		24,705	0
Liabilities at fair value: [Abstract]
Other liabilities		0	0
Total liabilities at fair value		0	0
Recurring | Models with significant observable market parameters (Level 2)
Assets, Fair Value Disclosure [Abstract]
U.S. treasury securities		251	250
U.S. government agency securities		61,900	21,769
Mortgage-backed securities		1,539,050	976,626
State and municipal securities		533,602	212,720
Agency-backed securities		190,220	78,580
Corporate notes and other		77,306	8,601
Total investment securities available-for-sale		2,402,329	1,298,546
Other investments		0	0
Other assets		12,601	13,340
Total assets at fair value		2,414,930	1,311,886
Liabilities at fair value: [Abstract]
Other liabilities		16,190	15,758
Total liabilities at fair value		16,190	15,758
Recurring | Models with significant unobservable market parameters (Level 3)
Assets, Fair Value Disclosure [Abstract]
U.S. treasury securities		0	0
U.S. government agency securities		0	0
Mortgage-backed securities		0	0
State and municipal securities		0	0
Agency-backed securities		0	0
Corporate notes and other		0	0
Total investment securities available-for-sale		0	0
Other investments		27,850	10,478
Other assets		0	0
Total assets at fair value		27,850	10,478
Liabilities at fair value: [Abstract]
Other liabilities		0	0
Total liabilities at fair value		0	0
Nonrecurring
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Other real estate owned		24,806	6,090
Nonaccrual loans, net	[2]	38,811	26,506
Total		63,617	32,596
Total losses on other real estate owned		(66)	(135)
Total losses on collateral dependent nonaccrual loans, net	[2]	(3,410)	(7,173)
Total losses for the year-to-date period then ended		(3,476)	(7,308)
Nonrecurring | Quoted market prices in an active market (Level 1)
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Other real estate owned		0	0
Nonaccrual loans, net	[2]	0	0
Total		0	0
Nonrecurring | Models with significant observable market parameters (Level 2)
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Other real estate owned		0	0
Nonaccrual loans, net	[2]	0	0
Total		0	0
Nonrecurring | Models with significant unobservable market parameters (Level 3)
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Other real estate owned		24,806	6,090
Nonaccrual loans, net	[2]	38,811	26,506
Total		$ 63,617	$ 32,596

[1] Collateral dependent loans are typically charged-off to their net realizable value and no specific allowance is carried related to those loans.

[2] Amount is net of valuation allowance of $1.4 million and $1.1 million at June 30, 2017 and December 31, 2016, respectively, as required by ASC 310-10, "Receivables."