Performance Incentive Plan (Restricted Stock Activity) (Details)	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Number of Shares
Restricted shares granted (in shares) | shares	35,251
Weighted Average Share Price
Restricted shares granted (in dollars per share) | $ / shares	$ 32.27
Restricted stock
Number of Shares
Non-vested restricted shares, January 1 (in shares) | shares	903,351
Restricted shares granted (in shares) | shares	288,422
Restricted shares vested (in shares) | shares	(270,713)
Restricted shares forfeited (in shares) | shares	(25,016)
Non-vested restricted shares, December 31 (in shares) | shares	896,044
Weighted Average Share Price
Non-vested restricted shares, January 1 (in dollars per share) | $ / shares	$ 44.77
Restricted shares granted (in dollars per share) | $ / shares	55.68
Restricted shares vested (in dollars per share) | $ / shares	41.21
Restricted shares forfeited (in dollars per share) | $ / shares	38.21
Non-vested restricted shares, December 31 (in dollars per share) | $ / shares	$ 49.54