Share-Based Compensation - Summary of Information Of SERP (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
SERP expense	$ 6,865	$ 5,900	$ 5,985
SERP
Defined Benefit Plan Disclosure [Line Items]
SERP expense	$ 539	$ 547	$ 503
Treasury shares issued to fund SERP expense (in shares)	22	14	9
SERP trust account balance at December 31	$ 43,952	$ 39,766	$ 42,467
Unrealized gain (loss) recorded in SERP liability account	$ 7,353	$ (1,469)	$ 4,534