Net Income Per Common Share (Narrative) (Details) - $ / shares	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2020
Net Income Per Common Share [Abstract]
Employee stock options excluded from calculations of diluted net income per share	9,091,179	9,464,482
Number Of SharesTo Be Issued Basic Stock Purchase Contracts		9,091,179
Treshold	$ 42.41	$ 42.41

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration