Common Stock (Tables)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Schedule of Changes in Common Stock

Changes in common stock for each period are as follows (in thousands):

	Year Ended December 31,
	2017					2016
	Shares			Amount		Shares		Amount
Common stock at the beginning of the period		35,048,338		$	416		34,568,942	$	411
Exercise of stock options		539,183			6		296,103		3
Settlement of restricted stock units		397,522			4		183,293		2
Acquisitions of treasury stock		(1,795,444	)		—		—		—
Total common stock outstanding at the end of the period		34,189,599		$	426		35,048,338	$	416