Income per Share (Summary of Basic and Diluted Earnings 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
Income per Share
Net income available to common stockholders	$ 315,577	$ 49,827	$ 31,738	$ 95,869	$ 31,230	$ 67,268	$ 65,134	$ 86,298	$ 493,011	$ 249,930	$ 173,148
Weighted average shares outstanding-basic (shares)									208,325,823	206,035,408	174,059,386
Potentially dilutive common shares:
Unvested incentive units (shares)									165,185	141,260	141,136
Forward equity offering (shares)									813,073	33,315	124,527
Market performance-based awards (shares)									158,166	463,488	570,049
Weighted average shares/units outstanding-diluted (shares/units)									209,462,247	206,673,471	174,895,098
Income per share:
Basic (in dollars per share)	$ 1.51	$ 0.24	$ 0.15	$ 0.46	$ 0.15	$ 0.33	$ 0.32	$ 0.42	$ 2.37	$ 1.21	$ 0.99
Diluted (in dollars per share)	$ 1.50	$ 0.24	$ 0.15	$ 0.46	$ 0.15	$ 0.33	$ 0.32	$ 0.42	$ 2.35	$ 1.21	$ 0.99