Stockholders' Equity and Partners' Capital - Narrative (Details) - USD ($)
1 Months Ended 3 Months Ended 6 Months Ended
May 29, 2018
Mar. 05, 2018
May 31, 2018
Aug. 31, 2017
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Subsidiary, Sale of Stock [Line Items]                  
Shares withheld for taxes             200,000    
Shares withheld for taxes, value             $ 1,700,000    
Preferred stock, shares outstanding         6,900,000   6,900,000   6,900,000
Dividend rate             6.00%    
Liquidation value (in dollars per share)         $ 25   $ 25    
Dividend rate, quarterly basis (in dollars per share)             0.375    
Dividend rate, annual basis (in dollars per share)             $ 1.5    
Less: dividends paid to preferred stockholders         $ 2,588,000 $ 0 $ 5,176,000 $ 0  
Dividends, preferred stock $ 2,588,000 $ 2,588,000         $ 5,176,000    
Stock repurchase program, authorized amount     $ 250,000,000 $ 250,000,000          
Stock repurchase program, period in force     18 months 18 months          
Stock repurchased during period (in shares)             21,200,000    
Stock repurchased, weighted average price (in dollars per share)             $ 7.90    
Stock repurchase program, remaining authorized repurchase amount         0   $ 0    
Stock repurchased, fees acquired             $ 500,000    
ATM Program, November 2016                  
Subsidiary, Sale of Stock [Line Items]                  
Issuance of common shares (in shares)             0    
Gross proceeds capacity remaining         $ 500,000,000   $ 500,000,000