Earnings Per Share - Potentially Dilutive Securities (Details) - shares	3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Dec. 31, 2017
RSUs
Incremental Weighted Average Shares Attributable to Dilutive Effect
Antidilutive securities excluded from computation of diluted earnings per share	111,536	0	25,648	0
Performance share units
Incremental Weighted Average Shares Attributable to Dilutive Effect
Antidilutive securities excluded from computation of diluted earnings per share	118,215	0	0	0
Common stock | Stock options
Incremental Weighted Average Shares Attributable to Dilutive Effect
Antidilutive securities excluded from computation of diluted earnings per share	877,015	623,570	595,813	636,099