Consolidated Balance Sheets (Unaudited) - Parenthetical - shares	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Statement of Financial Position [Abstract]
Common stock, shares outstanding (in shares)	28,781,000	28,736,000	28,644,000
Common stock, shares authorized (in shares)	100,000,000	100,000,000	100,000,000
Common stock, shares issued (in shares)	28,781,000	28,736,000	28,644,000