Earnings per Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Basic earnings per share
Net income	$ 16,964	$ 7,676	$ 34,991	$ 15,602
Average common stock outstanding (in shares)	47,164,909	42,841,152	47,058,958	40,851,273
Net income per share (in dollars per share)	$ 0.36	$ 0.18	$ 0.74	$ 0.38
Diluted earnings per share
Net income	$ 16,964	$ 7,676	$ 34,991	$ 15,602
Average common stock outstanding (in shares)	47,164,909	42,841,152	47,058,958	40,851,273
Add: Dilutive effect of employee restricted stock and stock options (in shares)	809,209	715,133	768,688	687,496
Average shares outstanding - diluted (in shares)	47,974,118	43,556,285	47,827,646	41,538,769
Net income per share (in dollars per share)	$ 0.35	$ 0.18	$ 0.73	$ 0.38