Leasing (Net Rent Expense) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leases, Rent Expense, Net [Abstract]
Minimum operating lease expense	$ 254,565	$ 247,039	$ 234,113
Contingent rents	759	701	744
Other lease related occupancy costs	11,688	11,257	10,043
Total rent expense	267,012	258,997	244,900
Less: sublease income	3,984	4,105	4,031
Net rent expense	$ 263,028	$ 254,892	$ 240,869