Stockholders' Equity Matters - Dividends Declared (Details)														3 Months Ended		6 Months Ended
	Jul. 02, 2018 USD ($)	May 24, 2018 $ / shares	Apr. 02, 2018 USD ($)	Feb. 14, 2018 $ / shares	Jan. 02, 2018 USD ($)	Dec. 12, 2017 USD ($) bank $ / shares shares	Oct. 24, 2017 $ / shares	Oct. 02, 2017 USD ($)	Jul. 27, 2017 $ / shares	Jul. 03, 2017 USD ($)	May 24, 2017 $ / shares	Apr. 03, 2017 USD ($)	Feb. 15, 2017 $ / shares	Jun. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2017 $ / shares	Jun. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2017 USD ($) $ / shares	Dec. 31, 2017 $ / shares shares	Oct. 31, 2017 USD ($)
Subsidiary or Equity Method Investee [Line Items]
Dividends Declared per Common Share (in dollars per share) | $ / shares		$ 0.5875		$ 0.5875			$ 0.5875		$ 0.55		$ 0.55		$ 0.55	$ 0.5877	$ 0.5504	$ 1.1765	$ 1.1008
Dividends, Common Stock	$ 168,078,000		$ 167,969,000		$ 166,319,000			$ 146,772,000		$ 145,417,000		$ 145,235,000				$ 338,251,000	$ 291,729,000
Common stock, issued shares | shares														286,099,227		286,099,227		283,110,183
Common Stock, Par or Stated Value Per Share | $ / shares														$ 0.01		$ 0.01		$ 0.01
At The Market (ATM) Equity Program [Member]
Subsidiary or Equity Method Investee [Line Items]
Sale of Stock, Authorized Amount																			$ 500,000,000
Common stock, issued shares | shares														273,486		273,486
Sale Of Stock Consideration Received On Transaction, Gross														$ 8,800,000
Sale of Stock, Consideration Received on Transaction														8,716,000
Payment of Stock Trading Commission Costs														90,000
Sale of Stock, Remaining Aggregate Sale Price Of Stock Available For Distribution														$ 431,200,000		$ 431,200,000
Number Of Banks						10
Equity Offering [Member]
Subsidiary or Equity Method Investee [Line Items]
Sale of Stock, Consideration Received on Transaction						$ 516,462,000
Number Of Banks | bank						16
Sale of Stock, Number of Shares Issued in Transaction | shares						14,500,000
Common Stock, Par or Stated Value Per Share | $ / shares						$ 37.00
Payments of Stock Issuance Costs Per Share | $ / shares						$ 1.38195
Over-Allotment Option [Member]
Subsidiary or Equity Method Investee [Line Items]
Sale of Stock, Consideration Received on Transaction					$ 76,200,000
Sale of Stock, Number of Shares Issued in Transaction | shares						2,175,000