Stock Compensation Plans and Other Employee Benefit Plans (Summary of Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Shares
Outstanding at beginning of the period (in shares)	795,014	1,084,756	1,698,912
Granted (in shares)	0	0	0
Options outstanding in acquired plans (in shares)	106,748
Exercised (in shares)	(146,430)	(282,614)	(593,459)
Forfeited or canceled (in shares)	0	(7,128)	(20,697)
Outstanding at end of the period (in shares)	755,332	795,014	1,084,756
Exercisable (in shares)	735,396	613,932	562,810
Vested or expected to vest (in shares)	755,332
Weighted Average Strike Price
Outstanding at beginning of the period (in dollars per share)	$ 42.25	$ 41.98	$ 41.50
Granted (in dollars per share)	0	0	0
Options outstanding in acquired plans (in dollars per share)	38.83
Exercised (in dollars per share)	38.84	41.25	40.57
Forfeited or canceled (in dollars per share)	0	39.84	42.83
Outstanding at end of the period (in dollars per share)	42.43	42.25	41.98
Exercisable (in dollars per share)	42.42	$ 42.54	$ 41.82
Vested or expected to vest (in dollars per share)	$ 42.43
Stock Options Additional Disclosures
Outstanding, remaining contractual term	2 years 9 months 18 days	3 years 1 month 6 days	4 years
Outstanding, intrinsic value	$ 21,503	$ 19,268	$ 43,817
Exercisable, remaining contractual term	2 years 8 months 12 days	3 years 1 month 6 days	3 years 3 months 18 days
Exercisable, intrinsic value	$ 20,947	$ 14,705	$ 22,820
Vested or expected to vest, remaining contractual term	2 years 9 months 18 days
Vested or expected to vest, intrinsic value	$ 21,503