Pension Arrangements (Fair Value Measurement Information U.K. Pension Plan Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	$ 410,928	$ 397,469	$ 336,189
Quoted Pricesin Active Markets (Level 1) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	311,554
Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	99,374
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	0
Growth assets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	247,393	280,019
Growth assets | Quoted Pricesin Active Markets (Level 1) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	176,219
Growth assets | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	71,174
Growth assets | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	0
Debt securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	158,436	113,393
Debt securities | Quoted Pricesin Active Markets (Level 1) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	133,212
Debt securities | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	25,224
Debt securities | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	0
Debt securities | Corporate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	37,929	30,774
Debt securities | Corporate [Member] | Quoted Pricesin Active Markets (Level 1) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	12,705
Debt securities | Corporate [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	25,224
Debt securities | Corporate [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	0
Debt securities | Index-Linked [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	120,507	82,619
Debt securities | Index-Linked [Member] | Quoted Pricesin Active Markets (Level 1) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	120,507
Debt securities | Index-Linked [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	0
Debt securities | Index-Linked [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	0
Real estate mutual funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	2,976	2,746
Real estate mutual funds | Quoted Pricesin Active Markets (Level 1) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	0
Real estate mutual funds | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	2,976
Real estate mutual funds | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	0
Cash and cash equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	2,123	1,311
Cash and cash equivalents | Quoted Pricesin Active Markets (Level 1) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	2,123
Cash and cash equivalents | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	0
Cash and cash equivalents | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value of plan assets	$ 0