Goodwill and Core Deposit Intangibles (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
	Oct. 01, 2015	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Mar. 31, 2016
Goodwill
Beginning of period		$ 85,291	$ 30,129	$ 30,129
Add acquisition				55,162
End of the period		85,291		85,291
Core Deposit Intangibles RollForward
Beginning of period		11,562	4,148	4,148
Add acquisition				8,261
Less amortization		(402)	(148)	(847)
End of period		11,160		11,562
Expected future amortization expense
Finite-Lived Intangible Assets, Net, Total		11,562	$ 4,148	$ 4,148	$ 11,160
Core deposit intangibles
Core Deposit Intangibles RollForward
End of period		11,160
Expected future amortization expense
2016					1,185
2017					1,472
2018					1,196
2019					1,080
2020					992
Thereafter					5,235
Finite-Lived Intangible Assets, Net, Total		$ 11,160			$ 11,160
Core deposit intangibles | Minimum
Core Deposit Intangibles RollForward
Finite-Lived Intangible Asset, Useful Life		6 years
Core deposit intangibles | Maximum
Core Deposit Intangibles RollForward
Finite-Lived Intangible Asset, Useful Life		19 years
Patriot Bancshares Inc
Goodwill
Add acquisition	$ 55,200