EPS Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Net income	$ 78,060	$ 78,070
Dividends declared on preferred stock	(3,750)	(3,750)
Dividends, dividend equivalents and undistributed earnings allocated to participating securities	(431)	(395)
Net income to common stockholders - basic and diluted	$ 73,879	$ 73,925
Denominator:
Weighted average common shares for basic and diluted earnings per share (in shares)	372,579,000	370,942,000
Basic and diluted earnings per share (in dollars per share)	$ 0.20	$ 0.20
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	2,300,000
Restricted shares of common stock
Denominator:
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	22,000
Weighted average grant date fair value (in dollars per share)	$ 7.12
RSUs
Denominator:
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	2,300,000
Weighted average grant date fair value (in dollars per share)	$ 6.50