Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2019
Significant Accounting Policies [Abstract]
Cash and Cash Equivalents	All highly liquid investments with maturity of three months or less when purchased are considered to be cash equivalents. The carrying value of a cash equivalent approximates its fair value based on its nature. At June 30, 2019, December 31, 2018, and June 30, 2018, all cash and cash equivalents were invested in a United States Treasury money market fund, of which an affiliate of the Company serves as the investment manager.
Marketable Securities	The Company may from time to time invest in marketable securities that are bought and held principally for the purpose of selling them in the near term and are classified as trading securities. Trading securities are recorded at fair value on the balance sheet in current assets, with the change in fair value during the period included in earnings.
Earnings Per Share	Basic earnings per share is based on the weighted-average number of common shares outstanding during each period. Diluted earnings per share is based on basic shares plus the incremental shares that would be issued upon the assumed exercise of in-the-money stock options and unvested restricted stock using the treasury stock method, and if dilutive.

Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2019

Significant Accounting Policies [Abstract]

All highly liquid investments with maturity of three months or less when purchased are considered to be cash equivalents. The carrying value of a cash equivalent approximates its fair value based on its nature.

At June 30, 2019, December 31, 2018, and June 30, 2018, all cash and cash equivalents were invested in a United States Treasury money market fund, of which an affiliate of the Company serves as the investment manager.

Marketable Securities

The Company may from time to time invest in marketable securities that are bought and held principally for the purpose of selling them in the near term and are classified as trading securities. Trading securities are recorded at fair value on the balance sheet in current assets, with the change in fair value during the period included in earnings.

Earnings Per Share

Basic earnings per share is based on the weighted-average number of common shares outstanding during each period. Diluted earnings per share is based on basic shares plus the incremental shares that would be issued upon the assumed exercise of in-the-money stock options and unvested restricted stock using the treasury stock method, and if dilutive.