Summary of Significant Accounting Policies (Details) - USD ($) shares in Thousands		3 Months Ended
	Jan. 01, 2019	Mar. 31, 2019	Mar. 31, 2018
Earnings per Share
Common stock equivalents (in shares)		503	290
Anti-dilutive common stock equivalents (in shares)		0	0
Risk of loss for each health insurance plan participant		$ 500,000
Accounting Standards Update 2018-15
Earnings per Share
Implementation costs capitalized		200,000
Accumulated amortization		0
Amortization expense		0
Accounting Standards Update 2018-02
Earnings per Share
Reclassification of stranded tax effects	$ 168,000	$ 0