Nature of Operations and Summary of Significant Accounting Policies - Basic and Diluted Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Basic EPS:
Net income available to common stockholders	$ 47,241	$ 20,360
Less: undistributed earnings to participating securities	0	127
Net income allocated to common stockholders	$ 47,241	$ 20,360
Net income allocated to common stockholders (in shares)	12,302	12,131
Net income allocated to common stockholders (in dollars per share)	$ 3.84	$ 1.67
Effect of dilutive securities:
Warrants to purchase common stock (in shares)	21	421
Plus: reallocation of undistributed earnings to participating securities		$ 5
Diluted EPS:
Net income allocated to common stockholders plus assumed conversions	$ 47,241	$ 20,238
Net income allocated to common stockholders plus assumed conversions (in shares)	12,372	12,600
Net income allocated to common stockholders plus assumed conversions (in dollars per share)	$ 3.82	$ 1.61
Restricted Stock
Effect of dilutive securities:
Non-vested restricted stock (in shares)	49	48
Distributed
Basic EPS:
Net income available to common stockholders	$ 47,241	$ 20,233
Net income allocated to common stockholders	$ 47,241	$ 20,233
Net income allocated to common stockholders (in shares)	12,302	12,131
Net income allocated to common stockholders (in dollars per share)	$ 3.84	$ 1.67