Description of the Business and Summary of Significant Accounting Policies - Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Income (Loss) Available to Common Stockholders, Diluted [Abstract]
Net income available to common shareholders	$ 44,654	$ 22,349	$ 49,383	$ 29,408	$ 159,194	$ 22,591	$ 55,546	$ 27,339	$ 145,794	$ 264,670	$ 176,100
Net income available to common stockholders - assuming dilution									$ 145,794	$ 264,670	$ 176,100
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted average shares outstanding - basic (in shares)									51,609,000	51,294,000	51,147,000
Effect of dilutive stock-based compensation (in shares)									169,000	213,000	224,000
Effect of dilutive put rights (in shares)									197,000
Net income available to common stockholders - assuming dilution (in shares)									51,975,000	51,507,000	51,371,000
Earnings Per Share, Diluted [Abstract]
Net income, per share (in dollars per share)	$ 0.86	$ 0.43	$ 0.96	$ 0.57	$ 3.10	$ 0.44	$ 1.08	$ 0.53	$ 2.82	$ 5.16	$ 3.44
Net income, per share - assuming dilution (in dollars per share)	$ 0.85	$ 0.43	$ 0.95	$ 0.57	$ 3.09	$ 0.44	$ 1.08	$ 0.53	$ 2.81	$ 5.14	$ 3.43
OP Units
Earnings Per Share, Diluted [Abstract]
Conversion of Stock, Shares Converted									1