Long-Term Debt (Long-Term Debt Phantom) (Details)	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2016 EUR (€)
EURIBOR
Long-Term Debt
Debt Instrument, Description of Variable Rate Basis	EURIBOR
LIBOR
Long-Term Debt
Debt Instrument, Description of Variable Rate Basis	LIBOR
$1.4 billion unsecured revolving credit facility, LIBOR plus 1.50%, currently 2.26% and a facility fee of 0.25%, due 2020
Long-Term Debt
Long term debt, principal amount	$ 1,400,000,000
Long term debt, current interest rate (as a percent)	2.26%	2.26%
Long term debt, facility fee (as a percent)	0.25%
Margin on floating rate base (as a percent)	1.50%
Long term debt, due date (year)	2020
$1.2 billion unsecured revolving credit facility, LIBOR plus 1.50%, currently 2.24% and a facility fee of 0.25%, due 2018
Long-Term Debt
Long term debt, principal amount	$ 1,200,000,000
Long term debt, current interest rate (as a percent)	2.24%	2.24%
Long term debt, facility fee (as a percent)	0.25%
Margin on floating rate base (as a percent)	1.50%
Long term debt, due date (year)	2018
Unsecured senior notes and senior debentures, 5.25% to 7.50%, due 2018, 2022 and 2027 | Lower Limit
Long-Term Debt
Long term debt, stated interest rate (as a percent)	5.25%	5.25%
Unsecured senior notes and senior debentures, 5.25% to 7.50%, due 2018, 2022 and 2027 | Lower Limit | Period 1
Long-Term Debt
Long term debt, stated interest rate (as a percent)	5.25%	5.25%
Unsecured senior notes and senior debentures, 5.25% to 7.50%, due 2018, 2022 and 2027 | Lower Limit | Period 2
Long-Term Debt
Long term debt, stated interest rate (as a percent)	5.25%	5.25%
Unsecured senior notes and senior debentures, 5.25% to 7.50%, due 2018, 2022 and 2027 | Lower Limit | Period 3
Long-Term Debt
Long term debt, stated interest rate (as a percent)	5.25%	5.25%
Unsecured senior notes and senior debentures, 5.25% to 7.50%, due 2018, 2022 and 2027 | Upper Limit
Long-Term Debt
Long term debt, stated interest rate (as a percent)	7.50%	7.50%
Unsecured senior notes and senior debentures, 5.25% to 7.50%, due 2018, 2022 and 2027 | Upper Limit | Period 1
Long-Term Debt
Long term debt, stated interest rate (as a percent)	7.50%	7.50%
Long term debt, due date (year)	2018
Unsecured senior notes and senior debentures, 5.25% to 7.50%, due 2018, 2022 and 2027 | Upper Limit | Period 2
Long-Term Debt
Long term debt, stated interest rate (as a percent)	7.50%	7.50%
Long term debt, due date (year)	2022
Unsecured senior notes and senior debentures, 5.25% to 7.50%, due 2018, 2022 and 2027 | Upper Limit | Period 3
Long-Term Debt
Long term debt, stated interest rate (as a percent)	7.50%	7.50%
Long term debt, due date (year)	2027
$200 million unsecured term loan, LIBOR plus 1.30%, currently 2.06% due 2017
Long-Term Debt
Long term debt, principal amount	$ 200,000,000
Long term debt, current interest rate (as a percent)	2.06%	2.06%
Margin on floating rate base (as a percent)	1.30%
Long term debt, due date (year)	2017
$841.8 million unsecured term loan, LIBOR plus 1.00%, currently 2.26% due through 2028
Long-Term Debt
Long term debt, principal amount	$ 841,800,000
Long term debt, current interest rate (as a percent)	2.26%	2.26%
Margin on floating rate base (as a percent)	1.00%
Long term debt, due date (year)	2028
$226.1 million unsecured term loan, 2.53%, due through 2028
Long-Term Debt
Long term debt, principal amount	$ 226,100,000
Long term debt, current interest rate (as a percent)	2.53%	2.53%
Long term debt, due date (year)	2028
€700.7 million unsecured term loan, EURIBOR plus 1.15% currently 1.15%, due through 2028
Long-Term Debt
Long term debt, principal amount | €		€ 700,700,000
Long term debt, current interest rate (as a percent)	1.15%	1.15%
Margin on floating rate base (as a percent)	1.15%
Long term debt, due date (year)	2028
$742.1 million unsecured term loan, LIBOR plus 1.30%, currently 2.56%, due through 2027
Long-Term Debt
Long term debt, principal amount	$ 742,100,000.0
Long term debt, current interest rate (as a percent)	2.56%	2.56%
Margin on floating rate base (as a percent)	1.30%
Long term debt, due date (year)	2027
$273.2 million unsecured term loan, LIBOR plus 1.75%, currently 2.52%, due 2017
Long-Term Debt
Long term debt, principal amount	$ 273,200,000.0
Long term debt, current interest rate (as a percent)	2.52%	2.52%
Margin on floating rate base (as a percent)	1.75%
Long term debt, due date (year)	2017
$519 million unsecured term loan, LIBOR plus 0.45%, currently 1.71%, due through 2020
Long-Term Debt
Long term debt, principal amount	$ 519,000,000
Long term debt, current interest rate (as a percent)	1.71%	1.71%
Margin on floating rate base (as a percent)	0.45%
Long term debt, due date (year)	2020
$420 million unsecured term loan, 5.41%, due through 2021
Long-Term Debt
Long term debt, principal amount	$ 420,000,000
Long term debt, stated interest rate (as a percent)	5.41%	5.41%
Long term debt, due date (year)	2021
$420 million unsecured term loan, LIBOR plus 1.65%, currently 2.91%, due through 2021
Long-Term Debt
Long term debt, principal amount	$ 420,000,000
Long term debt, current interest rate (as a percent)	2.91%	2.91%
Margin on floating rate base (as a percent)	1.65%
Long term debt, due date (year)	2021
€159.4 million unsecured term loan, EURIBOR plus 1.58%, currently 1.58%, due through 2021
Long-Term Debt
Long term debt, principal amount | €		€ 159,400,000.0
Long term debt, current interest rate (as a percent)	1.58%	1.58%
Margin on floating rate base (as a percent)	1.58%
Long term debt, due date (year)	2021
$524.5 million unsecured term loan, LIBOR plus 0.50%, currently 1.48%, due through 2021
Long-Term Debt
Long term debt, principal amount	$ 524,500,000.0
Long term debt, current interest rate (as a percent)	1.48%	1.48%
Margin on floating rate base (as a percent)	0.50%
Long term debt, due date (year)	2021
$566.1 million unsecured term loan, LIBOR plus 0.37%, currently 1.63%, due through 2022
Long-Term Debt
Long term debt, principal amount	$ 566,100,000.0
Long term debt, current interest rate (as a percent)	1.63%	1.63%
Margin on floating rate base (as a percent)	0.37%
Long term debt, due date (year)	2022
$1.1 billion unsecured term loan, LIBOR plus 1.65%, currently 2.91%, due through 2022
Long-Term Debt
Long term debt, principal amount	$ 1,100,000,000
Long term debt, current interest rate (as a percent)	2.91%	2.91%
Margin on floating rate base (as a percent)	1.65%
Long term debt, due date (year)	2022
$632.0 million unsecured term loan, LIBOR plus 0.40%, currently 1.38%, due through 2023
Long-Term Debt
Long term debt, principal amount	$ 632,000,000
Long term debt, current interest rate (as a percent)	1.38%	1.38%
Margin on floating rate base (as a percent)	0.40%
Long term debt, due date (year)	2023
$673.5 million unsecured term loan, LIBOR plus 0.40%, currently 1.66%, due through 2024
Long-Term Debt
Long term debt, principal amount	$ 673,500,000.0
Long term debt, current interest rate (as a percent)	1.66%	1.66%
Margin on floating rate base (as a percent)	0.40%
Long term debt, due date (year)	2024
$65.0 million unsecured term loan, LIBOR plus 1.75%, currently 2.52%, due through 2019
Long-Term Debt
Long term debt, principal amount	$ 65,000,000
Long term debt, current interest rate (as a percent)	2.52%	2.52%
Margin on floating rate base (as a percent)	1.75%
Long term debt, due date (year)	2019
$380.0 million unsecured term loan, LIBOR plus 1.75%, currently 2.52%, due 2018
Long-Term Debt
Long term debt, principal amount	$ 380,000,000
Long term debt, current interest rate (as a percent)	2.52%	2.52%
Margin on floating rate base (as a percent)	1.75%
Long term debt, due date (year)	2018
$791.1 million unsecured term loan, LIBOR plus 1.30%, currently 2.56%, due through 2026
Long-Term Debt
Long term debt, principal amount	$ 791,100,000.0
Long term debt, current interest rate (as a percent)	2.56%	2.56%
Margin on floating rate base (as a percent)	1.30%
Long term debt, due date (year)	2026
$290.0 million unsecured term loan, LIBOR plus 1.75%, currently 2.52%, due 2018
Long-Term Debt
Long term debt, principal amount	$ 290,000,000
Long term debt, current interest rate (as a percent)	2.52%	2.52%
Margin on floating rate base (as a percent)	1.75%
Long term debt, due date (year)	2018
€365 million unsecured term loan, EURIBOR plus 1.75%, currently 1.75%, due 2017
Long-Term Debt
Long term debt, principal amount | €		€ 365,000,000
Long term debt, current interest rate (as a percent)	1.75%	1.75%
Margin on floating rate base (as a percent)	1.75%
Long term debt, due date (year)	2017
$7.3 million unsecured term loan, LIBOR plus 2.5%, currently 3.76%, due through 2023
Long-Term Debt
Long term debt, principal amount	$ 7,300,000.0
Long term debt, current interest rate (as a percent)	3.76%	3.76%
Margin on floating rate base (as a percent)	2.50%
Long term debt, due date (year)	2023
$30.3 million unsecured term loan, LIBOR plus 3.75%, currently 4.70%, due through 2021
Long-Term Debt
Long term debt, principal amount	$ 30,300,000.0
Long term debt, current interest rate (as a percent)	4.70%	4.70%
Margin on floating rate base (as a percent)	3.75%
Long term debt, due date (year)	2021