Significant Accounting Policies - Shares Used in Computation of Basic and Diluted Per Share Information (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accounting Policies [Abstract]
Weighted average number of shares outstanding for basic per share calculation (in shares)	31,104	30,960	31,060	30,899
Effect of dilutive potential shares:
Nonvested stock (in shares)	220	241	241	289
Adjusted weighted average shares for diluted per share calculation (in shares)	31,324	31,201	31,301	31,188
Anti-dilutive shares (in shares)	5	13	122	153