Earnings Per Common Share Calculation of Numerator and Denominator in EPS table (Details) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Numerators:
Net income available to Common Stockholders—Basic (shares)	$ 54,952	$ 64,461	$ 46,401	$ 113,309	$ 50,166	$ 56,070	$ 46,137	$ 60,222	$ 279,123	$ 212,596	$ 189,904
Amounts allocated to dilutive securities (shares)									16,783	13,774	12,788
Net income available to Common Stockholders—Fully Diluted (shares)									$ 295,906	$ 226,370	$ 202,692
Denominator:
Weighted average Common Shares outstanding – Basic (shares)	181,664	181,649	180,312	179,560	179,140	178,400	177,098	177,048	180,805	177,928	173,994
Effect of dilutive securities:
Exchange of Common OP Units for Common Shares (shares)									10,934	11,586	12,066
Stock options and restricted stock (shares)									256	596	790
Weighted average Common Shares outstanding – Fully Diluted (shares)	192,458	192,400	191,860	191,248	191,154	190,526	189,246	189,154	191,995	190,110	186,850
Earnings per Common Share – Basic (usd per share)	$ 0.30	$ 0.35	$ 0.26	$ 0.63	$ 0.28	$ 0.31	$ 0.26	$ 0.34	$ 1.54	$ 1.19	$ 1.09
Earnings per Common Share – Fully Diluted (usd per share)	$ 0.30	$ 0.35	$ 0.26	$ 0.63	$ 0.28	$ 0.31	$ 0.26	$ 0.34	$ 1.54	$ 1.19	$ 1.08