Equity and Accumulated Other Comprehensive Loss, Net (Redeemable Preferred Stock) (Details) $ / shares in Units, $ in Thousands								12 Months Ended
	Sep. 14, 2017 $ / shares shares	Aug. 07, 2017 $ / shares shares	Apr. 05, 2017 USD ($) $ / shares shares	Aug. 24, 2015 $ / shares shares	Mar. 26, 2014 $ / shares shares	Apr. 09, 2013 $ / shares shares	Apr. 05, 2012 $ / shares shares	Dec. 31, 2017 USD ($) quarter $ / shares shares	Dec. 31, 2016 USD ($) shares
Class of Stock [Line Items]
Total liquidation value | $								$ 1,448,750
Shares outstanding as of December 31 | shares								50,650,000	41,900,000
Balance (net of issuance costs) as of December 31 | $								$ 1,249,560	$ 1,012,961
Preferred stock, liquidation preference per share (in dollars per share) | $ / shares								$ 25.00
Preferred stock, shares outstanding (in shares) | shares								50,650,000	41,900,000
Series C Preferred Stock
Class of Stock [Line Items]
Share cap (in shares) | shares	0.6389035
Total liquidation value | $								$ 201,250
Annual rate of dividend per share (in dollars per share) | $ / shares	$ 1.65625							$ 1.65625
Shares outstanding as of December 31 | shares								8,050,000	0
Balance (net of issuance costs) as of December 31 | $								$ 219,250	$ 0
Preferred stock, dividend rate	6.625%
Series F Preferred Stock
Class of Stock [Line Items]
Share cap (in shares) | shares							0.6843
Total liquidation value | $								$ 182,500
Annual rate of dividend per share (in dollars per share) | $ / shares							$ 1.65625	$ 1.65625
Shares outstanding as of December 31 | shares								0	7,300,000
Balance (net of issuance costs) as of December 31 | $								$ 0	$ 176,191
Number of quarters with no dividends triggering voting rights | quarter								6
Preferred stock, liquidation preference per share (in dollars per share) | $ / shares			$ 25.00
Preferred stock, shares outstanding (in shares) | shares			7,300,000
Preferred stock, redemption price per share (in dollars per share) | $ / shares			$ 25.01840
Redemption premium | $			$ 6,300
Series G Preferred Stock
Class of Stock [Line Items]
Share cap (in shares) | shares						0.7532
Total liquidation value | $								$ 250,000
Annual rate of dividend per share (in dollars per share) | $ / shares						$ 1.46875		$ 1.46875
Shares outstanding as of December 31 | shares								10,000,000	10,000,000
Balance (net of issuance costs) as of December 31 | $								$ 241,468	$ 241,468
Series H Preferred Stock
Class of Stock [Line Items]
Share cap (in shares) | shares					0.9632
Total liquidation value | $								$ 365,000
Annual rate of dividend per share (in dollars per share) | $ / shares					$ 1.84375			$ 1.84375
Shares outstanding as of December 31 | shares								14,600,000	14,600,000
Balance (net of issuance costs) as of December 31 | $								$ 353,290	$ 353,290
Series I Preferred Stock
Class of Stock [Line Items]
Share cap (in shares) | shares				0.76231
Total liquidation value | $								$ 250,000
Annual rate of dividend per share (in dollars per share) | $ / shares				$ 1.58750				$ 1.5875
Shares outstanding as of December 31 | shares								10,000,000	10,000,000
Balance (net of issuance costs) as of December 31 | $								$ 242,012	$ 242,012
Series J Preferred Stock
Class of Stock [Line Items]
Share cap (in shares) | shares		0.42521
Total liquidation value | $								$ 200,000
Annual rate of dividend per share (in dollars per share) | $ / shares		$ 1.31250						$ 1.3125
Shares outstanding as of December 31 | shares								8,000,000	0
Balance (net of issuance costs) as of December 31 | $								$ 193,540	$ 0