Earnings Per Share

Basic earnings per share is computed by dividing net income by the weighted-average number of shares of common stock outstanding during the period presented. Diluted earnings per share is computed by including the net increase in shares as if dilutive outstanding restricted stock awards were vested and stock options were exercised, using the treasury stock method.

Basic and diluted earnings per share has been computed based on the following:



	Years ended
(Dollars in thousands, except per share data)	December 31, 2018		December 31, 2017	December 31, 2016
Net income available to common stockholders, basic and diluted	$	181,878	116,377	121,131
Average outstanding shares - basic	83,603,515		77,537,664	76,278,463
Add: dilutive restricted stock awards and stock options	73,670		69,941	63,373
Average outstanding shares - diluted	83,677,185		77,607,605	76,341,836
Basic earnings per share	$	2.18	1.50	1.59
Diluted earnings per share	$	2.17	1.50	1.59

There were 1,357, 0 and 0 restricted stock awards and stock options excluded from the diluted average outstanding share calculation for the years ended December 31, 2018, 2017, and 2016, respectively. Anti-dilution occurs when the unrecognized compensation cost per share of a restricted stock award or the exercise price of a stock option exceeds the market price of the Company’s stock.