Employee Benefit Plans (Narrative) (Details) - USD ($) shares in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2012	Dec. 31, 2011	Jan. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant	6.2		6.2
Compensation cost related to restricted shares	$ 1,500,000	$ 1,100,000	$ 4,400,000	$ 3,600,000
Deferred compensation arrangement with individual, distributions paid								$ 4,500,000
Deferred compensation arrangement, vesting period						3 years	5 years
Deferred compensation arrangement, cash awards granted, amount	0		0		$ 8,900,000
Deferred compensation arrangement, compensation expense				5,400,000
Deferred compensation cash-based arrangement, liability	$ 100,000		$ 100,000		$ 12,800,000
Percentage of share of non-vested stock considered as call option	85.00%		85.00%
Percentage of share of non-vested stock considered as put-option			15.00%
Share-based payment award, vesting period			3 years		3 years
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 600,000	600,000		1,600,000
Deferred compensation share-based arrangement, liability	$ 300,000		$ 300,000		$ 7,900,000
Share-based payment award, vesting period			3 years
E S P P [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant	0.9		0.9
Allocated share-based compensation expense	$ 300,000	$ 300,000	$ 900,000	$ 700,000
Shares authorized for issuance	1.5		1.5
Scenario, Adjustment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation arrangement, compensation expense	$ (1,200,000)		$ (3,700,000)
Scenario, Adjustment [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense			$ (300,000)