Incentive Plan (Long-Term Incentive Units) (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2011	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term incentive units granted	181,801
Long-Term Incentive Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Share/unit compensation expense	$ 7.8	$ 2.2
Capitalized expense related to construction and leasing activities	0.5	0.4
Unearned compensation	$ 14.3		$ 12.9
Unearned compensation, period of recognition	2 years 7 months 6 days
Service And Performance Condition [Member] | Long-Term Incentive Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term incentive units granted	95,316
Number of shares satisfying the performance conditions	75,105