Capital Stock

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Capital Stock

(13) Capital Stock

We have authorized capital stock of 485.0 million shares, which includes 475.0 million shares of common stock and 10.0 million shares of preferred stock. The following is a schedule of changes in the number of common shares outstanding since the beginning of 2016:

	Year Ended December 31,
	2018		2017		2016
Beginning balance		248,129,430		247,144,356		169,316,460
MRD Merger		—		—		77,042,749
Restricted stock grants		865,095		539,096		490,609
Restricted stock units vested		434,046		344,937		266,541
Performance stock units issued		76,149		85,461		—
Shares retired		—		—		(739	)
Treasury shares		5,302		15,580		28,736
Ending balance		249,510,022		248,129,430		247,144,356

Common Stock Dividends

The board of directors declared quarterly dividends of $0.02 per common share for each of the four quarters of 2018, 2017 and 2016. The determination of the amount of future dividends, if any, to be declared and paid is at the sole discretion of the board of directors and will depend on our financial condition, earnings, capital requirements, levels of indebtedness, our future business prospects and other matters our board of directors deem relevant. Our bank credit facility and our senior subordinated notes allow for the payment of common dividends, with certain limitations.