Equity Incentive Plan - Restricted share activity (Details) - Restricted Stock [Member] shares in Thousands	9 Months Ended
	Sep. 30, 2021 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
Shares Outstanding, at beginning of the period | shares	175
Shares Outstanding, granted | shares	83
Shares Outstanding, vested | shares	(59)
Shares Outstanding, forfeited | shares	(24)
Shares Outstanding, at end of the period | shares	175
Weighted Average Grant Date Fair Value, at beginning of the period (in dollars per share) | $ / shares	$ 60.53
Weighted Average Grant Date Fair Value, granted (in dollars per share) | $ / shares	65.10
Weighted Average Grant Date Fair Value, vested (in dollars per share) | $ / shares	54.16
Weighted Average Grant Date Fair Value, forfeited (in dollars per share) | $ / shares	63.88
Weighted Average Grant Date Fair Value, Unvested restricted stock at end of the period (in dollars per share) | $ / shares	$ 64.40