Stock-Based Compensation - Summary of Nonvested Performance-based Share Awards (Details) - Nonvested shares	12 Months Ended
	Dec. 31, 2019
2019 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 14 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	14.00%
Nonvested Common Shares Earned	10.00%
2019 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 15%
Stock-based compensation
Compounded Annual Book Value Per Share Growth	15.00%
Nonvested Common Shares Earned	35.00%
2019 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 16 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	16.00%
Nonvested Common Shares Earned	60.00%
2019 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 17 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	17.00%
Nonvested Common Shares Earned	85.00%
2019 Performance-Based Grants | Maximum | Compounded Annual Book Value Per Share Growth 14 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	14.00%
Nonvested Common Shares Earned	0.00%
2019 Performance-Based Grants | Minimum | Compounded Annual Book Value Per Share Growth 18 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	18.00%
Nonvested Common Shares Earned	100.00%
2018 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 15%
Stock-based compensation
Compounded Annual Book Value Per Share Growth	15.00%
Nonvested Common Shares Earned	25.00%
2018 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 16 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	16.00%
Nonvested Common Shares Earned	50.00%
2018 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 17 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	17.00%
Nonvested Common Shares Earned	75.00%
2018 Performance-Based Grants | Maximum | Compounded Annual Book Value Per Share Growth 15%
Stock-based compensation
Compounded Annual Book Value Per Share Growth	15.00%
Nonvested Common Shares Earned	0.00%
2018 Performance-Based Grants | Minimum | Compounded Annual Book Value Per Share Growth 18 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	18.00%
Nonvested Common Shares Earned	100.00%
2017 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 16 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	16.00%
Nonvested Common Shares Earned	25.00%
2017 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 17 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	17.00%
Nonvested Common Shares Earned	50.00%
2017 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 18 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	18.00%
Nonvested Common Shares Earned	75.00%
2017 Performance-Based Grants | Maximum | Compounded Annual Book Value Per Share Growth 16 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	16.00%
Nonvested Common Shares Earned	0.00%
2017 Performance-Based Grants | Minimum | Compounded Annual Book Value Per Share Growth 19 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	19.00%
Nonvested Common Shares Earned	100.00%
2016 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 14 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	14.00%
Nonvested Common Shares Earned	50.00%
2016 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 15%
Stock-based compensation
Compounded Annual Book Value Per Share Growth	15.00%
Nonvested Common Shares Earned	75.00%
2016 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 13%
Stock-based compensation
Compounded Annual Book Value Per Share Growth	13.00%
Nonvested Common Shares Earned	25.00%
2016 Performance-Based Grants | Maximum | Compounded Annual Book Value Per Share Growth 13%
Stock-based compensation
Compounded Annual Book Value Per Share Growth	13.00%
Nonvested Common Shares Earned	0.00%
2016 Performance-Based Grants | Minimum | Compounded Annual Book Value Per Share Growth 16 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	16.00%
Nonvested Common Shares Earned	100.00%
2013, 2014 and 2015 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 14 %
Stock-based compensation
Compounded Annual Book Value Per Share Growth	14.00%
Nonvested Common Shares Earned	87.00%
2013, 2014 and 2015 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 16 %
Stock-based compensation
Nonvested Common Shares Earned	100.00%
2013, 2014 and 2015 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 13%
Stock-based compensation
Compounded Annual Book Value Per Share Growth	13.00%
Nonvested Common Shares Earned	61.00%
2013, 2014 and 2015 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 11%
Stock-based compensation
Compounded Annual Book Value Per Share Growth	11.00%
Nonvested Common Shares Earned	10.00%
2013, 2014 and 2015 Performance-Based Grants | Compounded Annual Book Value Per Share Growth 12%
Stock-based compensation
Compounded Annual Book Value Per Share Growth	12.00%
Nonvested Common Shares Earned	36.00%
2013, 2014 and 2015 Performance-Based Grants | Maximum | Compounded Annual Book Value Per Share Growth 11%
Stock-based compensation
Compounded Annual Book Value Per Share Growth	11.00%
Nonvested Common Shares Earned	0.00%
2013, 2014 and 2015 Performance-Based Grants | Minimum | Compounded Annual Book Value Per Share Growth 15%
Stock-based compensation
Compounded Annual Book Value Per Share Growth	15.00%
Nonvested Common Shares Earned	100.00%