Goodwill and Core Deposit Intangibles (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015
Goodwill
Beginning of period	$ 30,129	$ 15,672
End of the period	85,291	30,129	$ 15,672
Core Deposit Intangibles RollForward
Beginning of period	4,148
Less amortization	(847)	(303)	(246)
End of period	11,562	4,148
Expected future amortization expense
Finite-Lived Intangible Assets, Net, Total	4,148	4,148		$ 11,562
Core deposit intangibles
Core Deposit Intangibles RollForward
Beginning of period	4,148	984
Less amortization	(847)	(303)
End of period	11,562	4,148	984
Expected future amortization expense
2016				1,587
2017				1,472
2018				1,196
2019				1,080
2020				905
Thereafter				5,322
Finite-Lived Intangible Assets, Net, Total	$ 4,148	984	$ 984	$ 11,562
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
SP Bancorp Inc And Its Wholly Owned Subsidiary Share Plus Bank [Member]
Goodwill
Add acquisition		14,457
SP Bancorp Inc And Its Wholly Owned Subsidiary Share Plus Bank [Member] | Core deposit intangibles
Core Deposit Intangibles RollForward
Add acquisition		$ 3,467
Patriot Bancshares Inc
Goodwill
Add acquisition	$ 55,162
Patriot Bancshares Inc | Core deposit intangibles
Core Deposit Intangibles RollForward
Add acquisition	$ 8,261