Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) (Unaudited) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Dividend declared (in dollars per share)	$ 0.3700	$ 0.3250
Deferred compensation plan held Rabbi Trust (shares)	101,997	93,422	97,053	90,961
Preferred Stock, Shares Authorized	2,000,000		2,000,000
Preferred Stock, Par or Stated Value Per Share	$ 0.01		$ 0.01
Shares issued under the performance incentive plan withheld for employee taxes (shares)	7,635	10,436