Parent Company Financial Information - SUMMARY STATEMENTS OF CASH FLOWS (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Parent Company Financial Information
Net income	$ 11,953	$ 9,227	$ 10,369	$ 8,554	$ 8,065	$ 7,837	$ 7,825	$ 1,789	$ 40,103	$ 25,515	$ 16,616
Adjustments to reconcile net income to cash used in operating activities:
Share-based compensation expense									2,729	1,165	514
Increase in accrued expenses and other liabilities									(4,428)	6,786	2,764
Net cash provided by (used in) operating activities									63,447	23,669	13,188
Cash flows from financing activities:
Repurchase of common stock									(126)	(116)	(5,638)
Proceeds from issuance of subordinated debentures									0	0	58,834
Net increase (decrease) in cash and cash equivalents									78,440	(32,508)	(15,888)
Cash and cash equivalents, beginning of year				78,417				110,925	78,417	110,925	126,813
Cash and cash equivalents, end of year	156,857				78,417				156,857	78,417	110,925
Corporation
Parent Company Financial Information
Net income									40,103	25,515	16,616
Adjustments to reconcile net income to cash used in operating activities:
Share-based compensation expense									2,729	1,165	514
Equity in undistributed earnings of subsidiaries and dividends from the bank									(44,901)	(29,473)	(16,248)
Increase in accrued expenses and other liabilities									240	166	1,560
Increase (decrease) in current and deferred taxes									0	3,566	(286)
Decrease (increase) in other assets									4,794	(6,893)	232
Net cash provided by (used in) operating activities									2,965	(5,954)	2,388
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance cost									0	0	0
Repurchase of common stock									(125)	(116)	(5,638)
Proceeds from exercise of options and warrants									1,107	758	267
Capital contribution to Bank									7,765	(10,000)	(40,000)
Proceeds from issuance of subordinated debentures									0	0	58,834
Net cash provided (used in) financing activities									8,747	(9,358)	13,463
Net increase (decrease) in cash and cash equivalents									11,712	(15,312)	15,851
Cash and cash equivalents, beginning of year				$ 3,412				$ 18,724	3,412	18,724	2,873
Cash and cash equivalents, end of year	$ 15,124				$ 3,412				$ 15,124	$ 3,412	$ 18,724