Subsequent Events (Details) (2014 Credit Facility, Subsequent event, USD $) In Millions, unless otherwise specified	0 Months Ended
	Jul. 23, 2014
Subsequent events
Maximum borrowing capacity	$ 500.0
Extend additional term	1 year
Revolving loan borrowings
Subsequent events
Maximum borrowing capacity	250.0
Commitment commission (as a percent)	0.20%
Revolving loan borrowings | U.S. dollar denominated loans | Prime rate
Subsequent events
Borrowing margin (as a percent)	0.50%
Description of variable rate basis	Prime Rate
Revolving loan borrowings | U.S. dollar denominated loans | Overnight Federal Funds rate
Subsequent events
Borrowing margin (as a percent)	0.50%
Description of variable rate basis	Overnight Federal Funds Rate
Basis spread on variable rate (as a percent)	0.50%
Revolving loan borrowings | U.S. dollar denominated loans | Eurodollar rate for one month
Subsequent events
Borrowing margin (as a percent)	0.50%
Description of variable rate basis	Eurodollar rate for one month
Basis spread on variable rate (as a percent)	1.00%
Revolving loan borrowings | Eurodollar denominated loans | Eurodollar rate for selected interest period
Subsequent events
Borrowing margin (as a percent)	1.50%
Description of variable rate basis	Eurodollar rate for the selected interest period
Letter of credit
Subsequent events
Maximum borrowing capacity	70.0
Stated interest rate (as a percent)	1.625%
Term loan
Subsequent events
Maximum borrowing capacity	$ 250.0